Importance of Host Genetic Factors HLA and IL28B as Predictors of Response to Pegylated Interferon...

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The American Journal of GASTROENTEROLOGY VOLUME 106 | JULY 2011 www.amjgastro.com

INTRODUCTION Current therapy for chronic hepatitis C (CHC), a combination of

pegylated- α interferon (pegIFN- α ) and ribavirin (RBV), achieves a

response rate of 48 – 88 % ( 1 ). Viral factors, such as genotype, base-

line viral load, rapid virological response, early virological response,

and amino-acid pattern in the viral genome ( 2 – 4 ), and host factors,

including age, sex, race, liver fi brosis, and obesity, have been reported

to be associated with pegIFN- α / RBV therapy outcome ( 5 ).

Because pegIFN has direct antiviral eff ects and RBV promotes

a type 1 cytokine-mediated immune response that can enhance

antiviral immune responses, there might be an association

between immunogenetic characteristics and response to antiviral

therapy ( 6 ).

Strong, multispecifi c T-cell responses are thought to be mainly

responsible for viral elimination and disease pathogenesis during

hepatic C virus (HCV) infection ( 7 ). Th e eff ective presentation

of viral antigens to CD4 + and CD8 + T cells by HLA class I and

class II molecules, respectively, is the key regulator of optimum

immune response against viral infection. Two alleles are consis-

tently associated with viral clearance and the decreased disease

Importance of Host Genetic Factors HLA and IL28B as Predictors of Response to Pegylated Interferon and Ribavirin Paloma Mu ñ oz de Rueda , PhD 1 , 2 , 8 , Miguel- Á ngel L ó pez-Nevot , MD, PhD 3 , 8 , Pablo S á enz-L ó pez , PhD 3 , Jorge Casado , BS 1 , Antonia Mart í n-Casares 3 , Pablo Palomares , MD, PhD 1 , Rosa Quiles , PhD 1 , 2 , Ana Gila , MD, PhD 1 , 2 , Manuel Romero-G ó mez , MD, PhD 2 , 4 , Esther-Jos é Pav ó n , PhD 1 , Jos é -Antonio Mu ñ oz , PhD 1 , Á ngel Carazo , PhD 1 , Paloma Sanz-Cameno , PhD 2 , 5 , Ricardo Moreno-Otero , MD, PhD 2 , 5 , Mois é s Diago , MD, PhD 6 , Josefa Le ó n , PhD 1 , 2 , Á ngeles Ruiz-Extremera , MD, PhD 2 , 7 and Javier Salmer ó n , MD, PhD 1 , 2

OBJECTIVES: Viral factors are considered the best predictors of response to treatment for chronic hepatitis C (CHC), but genetic factors are known to have an important role in this respect. This paper investigates the relationships among the host genetic factors HLA and IL28B, viral factors, and the outcome of combination therapy.

METHODS: A multicenter retrospective cohort of 428 previously untreated CHC patients was treated with pegylated interferon / ribavirin (pegIFN / RBV) for 48 weeks. In all, 378 (88 % ) of these patients were genotype 1 or 4, and 50 (12 % ) were genotype 2 or 3.

RESULTS: Multivariate logistic regression showed the rs12979860 CC genotype (adjusted odds ratio (aOR) = 4.3, 95 % confi dence interval (95 % CI): 2.6 – 7), the HLA-DQB1 * 0301 allele (aOR = 2.08, 95 % CI: 1.2 – 3.5) and age, viral genotype, and viral load levels to be signifi cantly associated with sustained virological response (SVR). When the variable rs12979860 was eliminated, the area under the receiver operating characteristic (ROC) curve (AUC) decreased signifi cantly (0.76 vs. 0.69; P = 0.03). AUC values derived from viral factors were lower than those corresponding to host genetic factors (0.67 vs. 0.72, respectively; P = 0.04). The HLA-DQB1 * 0301 and A * 0201 alleles were associated with rs12979860 CC genotype and SVR ( P < 0.0001).

CONCLUSIONS: The HLA-DQB1 * 0301 allele and IL28B genotype are factors that are associated independently with SVR. There is a synergism between the HLA-DQB1 * 0301 and HLA-A * 0201 alleles with polymorphism rs12979860 CC, which increases the SVR rate. IL28B genotype is the best predictor of SVR.

SUPPLEMENTARY MATERIAL is linked to the online version of the paper at http://www.nature.com/ajg

Am J Gastroenterol 2011; 106:1246–1254; doi: 10.1038/ajg.2011.82; published online 14 June 2011

1 Unidad de Aparato Digestivo, Hospital Universitario San Cecilio , Granada , Spain ; 2 CIBEREHD (Instituto de Salud Carlos IIII) , Granada, Spain ; 3 Servicio de Inmunolog í a, Hospital Universitario Virgen de las Nieves , Granada , Spain ; 4 Unidad de Hepatolog í a, Hospital Ntra. Sra. de Valme , Sevilla , Spain ; 5 Unidad de Hepatology, Hospital Universitario de la Princesa , Madrid , Spain ; 6 Unidad de Hepatolog í a, Hospital General de Valencia , Valencia , Spain ; 7 Unidad de Pediatr í a, Hospital Universitario San Cecilio , Granada , Spain ; 8 These two authors contributed equally to this work . Correspondence: Paloma Mu ñ oz de Rueda, PhD, Unidad de Aparato Digestivo, Hospital Universitario San Cecilio , c / Dr Oloriz no16, 18012 Granada , Spain . E-mail: [email protected] Received 19 August 2010; accepted 11 February 2011

© 2011 by the American College of Gastroenterology The American Journal of GASTROENTEROLOGY

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HLA and IL28B Predict SVR in Patients With HCV

severity of hepatitis C: HLA-DQB1 * 0301 and HLA-DRB1 * 11, as

well as DRB1 * 11-DQB1 * 0301 haplotype ( 8 – 10 ). HLA associa-

tions with respect to IFN treatment response have been intensively

investigated across global populations. To date, a clear and repro-

ducible association has not been found between HLA alleles and

therapeutic outcome ( 11 – 13 ).

Very recently, another host genetic factor, a single-nucleotide

polymorphism on chromosome 19q13, rs12979860, has been

strongly associated with sustained virological response (SVR) to

treatment with pegIFN / RBV in a cohort of > 1,600 individuals

chronically infected with genotype 1 of the HCV ( 14 ). Th is vari-

ant is near the IL28B locus, which encodes type III IFN- λ 3. Th ese

authors state that the CC genotype in rs12979860 doubles the

chance of successful HCV treatment. Another study ( 15 ) found

that the CC genotype strongly enhances resolution of HCV infec-

tion among individuals of European or African ancestry. Accord-

ing to these results, rs12979860 polymorphism is the fi rst genetic

marker that predicts response to treatment for HCV genotype 1

in a genome-wide association study. IFN- λ 3, which belongs to

the type III family of IFNs, plays a role in innate immunity ( 16 ).

Type III IFNs are related to IL-10 and are similar to type I IFNs

with respect to their antiviral action ( 17,18 ).

Th e aim of this study was to explore the infl uence of the

host genetic factors (HLA class I A, B, and Cw loci and

HLA class II DRB1 and DQB1 loci and rs12979860 variations)

as predictive factors of SVR to pegIFN- α / RBV therapy for CHC

infection and to compare them with viral factors. A large cohort

of 428 Spanish Caucasian individuals was categorized through

molecular genotyping techniques for HLA and IL28B.

METHODS Patients A total of 428 previously untreated CHC patients were enrolled

in this multicenter retrospective cohort study. Th is cohort

included 378 patients (88 % ) with genotype 1 or 4 and 50 (12 % )

with genotype 2 or 3. Only 271 subjects had biopsy-proven

CHC. Th e histological study was carried out in accordance with

Scheuer ’ s grading of necroinfl ammatory activity (I0 – I8) and

fi brosis staging (F0 – F4), with modifi cations ( 19 ). Th e diagnosis

of CHC was based on the permanent detection of HCV-RNA

serum. Th e patients showed no evidence of hepatitis B virus,

HIV, alcoholism or autoimmune or drug-induced liver disease.

In all, 167 patients were treated at San Cecilio University Hospital

(Granada), 120 at Nuestra Se ñ ora de Valme Hospital (Sevilla), 101

at La Princesa Hospital (Madrid), and 40 at University General

Hospital (Valencia), all in Spain. All of these patients were treated

between 2001 and 2004.

Treatment and response to therapy Th e treatment consisted of 180 μ g / week pegIFN- α -2a (Pegasys,

Roche Diagnostics, PEGASYS ® , Roche, Basel, Switzerland) in combi-

nation with RBV dose-adjusted to body weight (800 – 1,200 mg / day;

Copegus, Roche Diagnostic) for 48 weeks. SVR was defi ned as

undetectable serum HCV-RNA 24 weeks aft er stopping treatment;

the patients whose HCV-RNA levels were detectable aft er the

completed period of treatment, together with relapsed responder

patients (undetectable HCV-RNA during treatment but detect-

able aft er discontinuation), were considered to have a non-SVR.

Subjects with insuffi cient viral response at 12 or 24 weeks discon-

tinued therapy per protocol as treatment failures and were consid-

ered to have a non-SVR.

Ethical considerations All subjects provided informed consent to participate and for

the collection and storage of serum and peripheral blood for

DNA extraction. Th e study protocol conformed to the ethical

guidelines of the 1975 Declaration of Helsinki. Prior approval for

the study was obtained from the applicable ethics committees.

Virological assays HCV genotyping was determined by reverse hybridization

(Inno-LIPA II HCV Innogenetics SA, Ghent, Belgium). Quanti-

tative measurement of viral load (cutoff < 15 IU / ml, HCV

Ampliprep TaqMan, Roche Molecular Systems, Pleasanton, CA)

was carried out at baseline and at weeks 12, 24, 48 (end of treat-

ment), and 72 (end of follow-up) with samples that were stored

at − 80 ° C.

HLA class I and HLA class II genotyping Class I HLA-A, B, and Cw loci and class II HLA-DRB1 and DQB1

loci genotyping was performed in 428 subjects. Geno typing was car-

ried out by SSO LABType (One Lambda, Canoga Park, CA). Target

DNA was amplifi ed by PCR using sequence-specifi c primers, fol-

lowed by hybridization with allele-specifi c oligo deoxynucleotides

coupled with fl uorescent phycoerythrin-labeled microspheres. Th e

fl uorescence intensity was determined on a Bio-Plex 200 system

(Luminex xMAP, Austin, TX). HLA allele assignment was per-

formed with HLA-Tools soft ware (Los Angeles, CA).

IL28B genotyping Rs12979860 genotyping was performed in 428 subjects using a

Taqman 5 ′ allelic discrimination assay (Custom Assay Service;

Ref AHI05OJ). Th e primers used were forward GCCTGTCGTGT

ACTGAACCA and backward GCGCGGAGTGCAATTCAAC.

Th e Taqman probes for the reverse strand were TGGTTC G CGC

CTTC labeled with VIC and CTGGTTC A CGCCTTC labeled

with FAM. Single-nucleotide polymorphism amplifi cation assays

were used according to the manufacturer ’ s instructions. PCR reac-

tions were carried out in a total volume of 4 μ l with the following

amplifi cation protocol: pre-incubation at 50 ° C for 2 min and at

95 ° C for 10 min, followed by 40 cycles of 95 ° C, 15 s; 60 ° C, 1 min.

Th e PCR results and genotype of each sample were automatically

attributed by the SDS 2.2.1 soft ware for allelic discrimination

(Applied Biosystems, Foster City, CA).

Statistical analysis Th e dependent variable was the viral response (non-SVR vs. SVR).

Th e degree of association between the response and independent

variables was determined by calculating the crude odds ratio (cOR)


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and its 95 % confi dence interval (CI). In the analysis of frequency of

the HLA class I and class II alleles according to the response, signi-

fi cant P values were corrected (Pc; Bonferroni ’ s correction) for the

number of alleles detected at each locus. When the dependent vari-

able was carrier vs. noncarrier of HLA-DQB1 * 0301 or rs12979860

CC vs. rs12979860 CT / TT genotype, the baseline variables were

compared between groups using the χ 2 test. To determine the

independent eff ect of each factor, the OR was adjusted (aOR) using

a binomial logistic regression model. Th e covariates included in

the multivariable model were age, sex, alanine aminotransferase,

γ -glutamyltransferase, viral genotype, viral load, HLA-DQB1 * 0301,

and IL28B. A histological study was not included because we only

had 271 biopsy-proven cases of CHC. Our model shows that:

P =+ − − + + + + +

1

1 1 04 1 17 0 88 0 8 0 73 1 47e xG xA xVL xDQ xIL( . . . . . . )

where P is the probability of achieving SVR, G is the viral geno-

type (genotype 1 or 4 = 0 and genotype 2 or 3 = 1), A is the patient ’ s

age ( > 40 years old = 0 and ≤ 40 years old = 1), VL is the viral

load ( > 600,000 IU / ml = 0 and ≤ 600,000 IU / ml = 1), DQ is HLA-

DQB1 * 0301 (HLA-DQB1 * 0301( − ) = 0 and HLA-DQB1 * 0301( + ) = 1

and IL is rs12979860 (rs12979860 CT / TT = 0 and rs12979860

CC = 1). Th e criterion for statistical signifi cance was P ≤ 0.05.

By means of diff erent models of logistic regression and receiver

operating characteristic (ROC) analysis, we studied the discrimina-

tory power of the diff erent predictive response factors to distinguish

individuals with SVR from those with non-SVR. Th us, the area under

the curve (AUC) ROC was independently obtained for the variables

age, viral load, viral genotype, HLA-DQB1 * 0301 (positive or nega-

tive), and rs12979860; in addition, four logistic models were studied:

model 1 used age, viral genotype, pre-treatment viral load, carrier of

HLA-DQB1 * 0301, and rs12979860 genotype; model 2 used all cov-

ariates except rs12979860 genotype; model 3 used genetic host fac-

tors (age + HLA-DQB1 * 0301 + rs12979860 genotype), and model 4

used viral factors (age + viral load + viral genotype). When the AUC

was ≥ 0.7, the model was considered to have predicted the response.

All statistical calculations were performed using SPSS soft ware

version 15.0 for Windows (SPSS Inc., Chicago, IL).

RESULTS Baseline clinical, virological, and histological characteristics and predictive factors of virological response Th e main clinical, virological, and histological features of all

428 patients are summarized in Table 1 . In bivariate analysis, the

factors associated with SVR were age ≤ 40 years old, viral geno-

type 2 or 3, γ -glutamyltransferase ≤ 37 U / l, and baseline viral load

≤ 600,000 IU / ml.

Study of HLA class I and class II and SVR association In the class I region, there were 35, 58, and 33 alleles at the

HLA-A, B and Cw loci, respectively. In the class II region, there

were 35 alleles at the HLA-DRB1 locus and 16 alleles at the

HLA-DQB1 locus. HLA-A * 0201, B * 4001, B * 4402, Cw * 0304,

DRB1 * 1101, and DQB * 0301 were associated with SVR, and

HLA-A * 0301, DRB1 * 0701, and DQB1 * 0202 were associated with

non-SVR, but when the P value was corrected (Bonferroni ’ s cor-

rection), only the P value for HLA-DQB1 * 0301 was statistically

signifi cant ( Table 2 ). In all, 100 of 428 patients had the HLA-

DQB1 * 0301 allele: 31 (31 % ) had a non-SVR and 69 (69 % ) had a

SVR; but in the HLA-DQB1 * 0301-negative group ( n = 328), 156

(48 % ) had a non-SVR and 172 (52 % ) had a SVR ( Table 2 ). Th e

characteristics of the HLA-DQB1 * 0301-positive and -negative

patients are shown in Supplementary Table I online, and those

of the HLA-DQB1 * 0301-positive patients ( n = 100) with SVR and

non-SVR are shown in Supplementary Table II .

Th e haplotype DRB1 * 1101-DQB1 * 0301 was studied on the

basis of the linkage disequilibrium between the HLA-DQB1 * 0301

and DRB1 * 1101 alleles. In all, 45 patients had the DRB1 * 1101-

DQB1 * 0301 haplotype, of whom 35 (78 % ) had SVR, whereas of

the 383 without this haplotype, 222 (58 % ) had SVR ( P = 0.03).

When the Bonferroni ’ s correction was applied, this result was no

longer statistically signifi cant.

When the patients were stratifi ed according to their viral geno-

type, the SVR rates in the HLA-DQB1 * 0301-positive and -negative

patients infected by viral genotype 1 or 4 were 68 % (60 / 88) and

48 % (140 / 290), respectively ( P = 0.001; Pc = 0.016); whereas in the

HLA-DQB1 * 0301-positive and -negative patients infected with

viral genotype 2 or 3 the corresponding values were 75 % (9 / 12)

and 84 % (32 / 38), respectively ( P = 0.4) (Mantel – Haenszel test,

P = 0.005). For an interaction term between viral genotype and

DQB1 * 0301 in logistic regression, P = 0.041.

Study of IL28B and association with SVR Rs12979860 genotypes were unequivocally assigned in all cases

except in fi ve individuals ( n = 423). Th e rs12979860 CC geno-

type frequency was 33 % ( n = 142), CT was 51 % ( n = 220), and TT

was 14 % ( n = 61). We found an association of the CC genotype

with SVR ( Table 2 ). When the patients were stratifi ed according

to viral genotype, the frequency of the CC genotype was higher

in viral genotype 2- or 3-infected patients (25 / 50; 50 % ) than in

viral genotype 1- or 4-infected patients (117 / 373; 31 % ; P = 0.009).

Th ere was a signifi cant association between genetic variation in

IL28B and SVR among individuals infected with viral genotype

1 or 4 ( P < 0.0001), but among those infected with viral genotype

2 or 3 no such association was found ( P = 0.7) (Mantel – Haenszel

test, P = 0.0001). Th e charac teristics of the rs12979860 CC and

CT / TT patients are shown in Supplementary Table III . Th e

rs12979860 CC genotype patients ( n = 142) with SVR vs. non-SVR

diff ered only with respect to viral load and baseline alanine amino-

transferase ( Table 3 ). However, the patients with CT / TT geno-

type and SVR were younger, had a lower γ -glutamyltransferase,

a lower viral load and a higher proportion of viral genotype 2 or 3

( Table 3 ). Accordingly, the patients with CT / TT genotype achieved

SVR only if they also presented other predictive factors.

Associations among HLA alleles, rs12979860 genotype, and SVR Th e associations between the HLA alleles found in our population

(126 HLA class I and 51 HLA class II alleles) and the rs12979860


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genotype were evaluated in SVR and non-SVR patients. Th e

HLA-DQB1 * 0301 and A * 0201 alleles ( Figure 1 ) were associ-

ated with the CC genotype and SVR. To establish whether any of

these alleles had a synergic eff ect with rs12979860 CC on SVR,

a simple logistic regression analysis with a polytomic variable

was performed for four groups of patients ( Figure 1 ). Th e

reference group was formed by patients without either of the two

alleles (HLA-DQB1 * 0301-negative or HLA-A * 0201-negative,

and rs12979860 CT / TT genotype). Patients who were HLA-DQB1 *

0301-positive and had the rs12979860 CC genotype ( n = 29) had

a 5.8 times greater probability of SVR than did those with neither

of the two. Note that HLA-DQB1 * 0301-positive and rs12979860

CT / TT genotype patients had a 2.9 times greater probability of

SVR than did those with neither of the two ( P < 0.0001). In all, 62

patients were HLA-A * 0201-positive and had the rs12979869 CC

genotype; 89 % of these achieved SVR, as opposed to 48 % of those

who had neither of these alleles ( P < 0.0001). Moreover, the HLA-

A * 0201-positive and rs12979869 CT / TT genotype patients did

not diff er signifi cantly from the patients without either of these

alleles ( Figure 1 ).

Table 1 . Baseline clinical and virological characteristics and histological features and predictive factors of sustained virological response

All patients, n =428 (100) Non-SVR, n =187 (44) SVR, n =241 (56) cOR a (95 % CI, P value)

Age (years)

≤ 40 164 (38) 51 (31) 113 (69) 2.35 (1.56 – 3.55, < 0.0001)

> 40 264 (62) 136 (51) 128 (49) 1

Sex

Female 180 (42) 85 (47) 95 (53) 1.28 (0.87 – 1.89, 0.21)

Male 248 (58) 102 (41) 146 (59) 1

Viral genotype

1 50 (12) 9 (18) 41 (82) 4.05 (1.92 – 8.58, < 0.0001)

1 or 4 378 (88) 178 (47) 200 (53) 1

Fibrosis stage ( n =271)

F0, F1 or F2 209 (77) 82 (39) 127 (61) 1.55 (0.88 – 2.74, 0.13)

F3 – F4 62 (23) 31 (50) 31 (50) 1

Necroinfl ammatory grade ( n =263 )

I0 – I4 164 (62) 65 (40) 99 (60) 1.27 (0.77 – 2.10, 0.35)

I5 – I8 99 (38) 45 (45) 54 (55) 1

ALT, U / l

≤ 40 44 (10) 20 (46) 24 (55) 0.91 (0.49 – 1.70, 0.76)

> 40 384 (90) 165 (43) 219 (57) 1

AST, U / l

≤ 40 133 (31) 55 (41) 78 (59) 1.14 (0.75 – 1.73, 0.53)

> 40 295 (69) 133 (45) 162 (55) 1

GGT, U / l

≤ 37 186 (44) 71 (38) 115 (62) 1.73 (1.16 – 2.58, 0.007)

> 37 242 (56) 126 (52) 116 (48) 1

Baseline viral load, IU / ml

≤ 600,000 141 (33) 41 (29) 100 (71) 2.35 (1.52 – 3.62, < 0.0001 )

> 600,000 287 (67) 146 (51) 141 (49) 1

ALT, alanine aminotransferase; AST, aspartate aminotransferase; CI, confi dence interval; cOR, crude odds ratio; GGT, γ glutamyltransferase; SVR, sustained virological response. Values are absolute with percentages in parentheses. a Logistic regression: reference groups, > 40 years old, male, viral genotype 1 or 4, fi brosis staging F3 – F4, necroinfl ammatory grade I5 – I8, ALT > 40 U / l, AST > 40 U / l, GGT > 37 U / l, viral load > 600,000 IU / ml.


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DISCUSSION A large number of studies have identifi ed viral- and patient-

related factors for pre-treatment prediction of the probability

of SVR ( 5 ). To date, the most important of these factors have

been the viral ones. Nevertheless, genetic host factors are seen

as becoming more important, with the development of high-

throughput technologies such as genome-wide association study.

Our study examines the eff ects of genetic diversity in the human

major histocompatibility complex (HLA-A, B, and C class I loci

and DRB1 and DQB1 class II loci) and the rs12979860 genotype

upstream of IL-28B on the outcome of pegIFN / RBV treatment.

Th e data used were obtained from a large ( n = 428) well-charac-

terized cohort of Spanish patients. We present evidence that there

is a signifi cant association of one class II allele HLA-DQB1 * 0301

and the rs12979860 CC genotype with SVR, the latter being

a better predictive factor of SVR than are viral factors.

Th e multivariate logistic regression model shows that age ≤ 40

years old, viral genotype 2 or 3, baseline viral load ≤ 600,000 IU / ml,

carrier of HLA-DQB1 * 0301 and rs12979860 CC genotype were

the main independent factors associated with SVR to pegIFN / RBV

therapy. All these variables, except HLA-DQB1 * 0301, were previ-

ously associated independently with SVR ( 14,20 – 23 ). As pegIFN

has direct antiviral eff ects and RBV promotes a type 1 cytokine-

mediated immune response that can enhance antiviral immune

responses, there might be an association of immunogenetic

characteristics with response to antiviral therapy. Accordingly, the

genetic variations at HLA loci with respect to antigen presentation

might be related to the response to pegIFN-based therapy.

In our review of relevant publications, we identifi ed only three

reports that examined whether specifi c HLA alleles were associ-

ated with SVR to pegIFN / RBV therapy for CHC infection ( 11 – 13 ).

Th e A * 02, B * 58, and DPB1 * 1701 HLA alleles were independently

associated with SVR by Rhodes et al. ( 11 ). Th e number of patients

was higher ( n = 343) ( 11 ), but they were separated into two races,

Caucasian Americans and African Americans, which diminished

the number of patients per arm, and allele frequencies were very

low in certain subgroups. However, what is most important is that

the P values were not corrected for the number of alleles found

in each locus ( 11 ). In fact, in our study, the HLA-A * 0201 allele

was statistically associated with SVR, but according to Bonferroni ’ s

correction this value was not signifi cant.

We found that the HLA class II allele DQB1 * 0301 is associated

with SVR, aft er adjusting and controlling for the most important

virological confounding factors. Previous studies have shown

that patients with higher levels of CD4 + T-cell responses are

more likely to develop SVR ( 24,25 ). It is assumed that the HLA-

DQB1 * 0301 allele may more eff ectively present HCV immuno-

dominant epitopes to CD4 + Th cells than do other alleles; indeed,

the immune-modulating epitope of HCV for the HLA-DQB1 * 0301

allele has been described ( http://www.hcv.lanl.gov ) ( 26 ), and this

allele was strongly associated with SVR in the current study. We

examined whether the presence of the DRB1 * 1101-DQB1 * 0301

haplotype might infl uence SVR, and found signifi cant diff erences;

however, following Bonferroni ’ s correction, this signifi cance disap-

peared. Th is fi nding corroborates the role of the HLA-DQB1 * 0301

Multivariate analysis model Figure 2 presents the aOR estimates for a logistic regression

model (model 1) including factors that were independently asso-

ciated with SVR. Table 4 shows the interindividual diff erences in

SVR obtained by the diff erent predictors in our model (Methods

section). Th e rs12979860 CC genotype was associated with a

more substantial diff erence in the rate of SVR than other baseline

predictors included in the model.

When the multivariate analysis was performed on the data for

267 patients for whom we were aware of the fi brosis stage, it was

found that fi brosis stage was not associated with SVR independ-

ently of the other factors (F0 – F2, aOR = 1.5, 95 % CI: 0.78 – 2.3,

P = 0.2).

Using ROC curve analysis, we sought to identify pre-treatment

variables that were predictive of SVR, and evaluated the power of

diff erent multivariate logistic models with diff erent predictors in

order to distinguish between SVR and non-SVR based on AUC

ROC ( Figure 3 ). Th e AUC for rs12979860 was greater than that

for HLA-DQB1 * 0301 and other covariates ( Figure 3a ). Model 1

(sensitivity and specifi city were 73 and 67 % , respectively) had

the largest AUC, as expected, because it included all the predic-

tive covariates ( Figure 3b ). When we extracted the variable

rs12979860 (model 2), the sensitivity and specifi city were 72 and

50 % , respectively, and the AUC was lower than in model 1 with

signifi cant diff erences ( P = 0.03). Comparison of the host genetic

factors model (model 3) and the viral factors model (model 4)

revealed statistically signifi cant diff erences (higher AUC in

model 3, P = 0.04) ( Figure 3b ).

Table 2 . HLA class I and II alleles with P value ≤ 0.05 before Bonferroni’s adjustment and rs12979860 genotype association with SVR

cOR a (95 % CI) P value Pc

HLA class I and II alleles ( n =428)

A*0201 ( + ) 1.738 (1.10 – 2.74) 0.02 0.7

A*0301 ( + ) 0.533 (0.31 – 0.91) 0.02 0.7

B*4001 ( + ) 5.345 (1.20 – 23.78) 0.02 1.1

B*4402 ( + ) 2.472 (1.03 – 5.918) 0.03 1.7

Cw*0304 ( + ) 4.315 (1.25 – 14.96) 0.02 0.6

DRB1*0701 ( + ) 0.529 (0.33 – 0.84) 0.007 0.2

DRB1*1101 ( + ) 2.2 (1.02 – 4.9) 0.04 1.4

DQB1*0202 ( + ) 0.589 (0.37 – 0.94) 0.03 0.48

DQB1*0301 ( + ) 2.02 (1.25 – 3.25) 0.003 0.04

IL28B ( n =423)

rs12979860 CC 3.84 (2.44 – 6.05) < 0.0001

CI, confi dence interval; cOR, crude odds ratio; Pc, Bonferroni’s correction; SVR, sustained virological response. a Logistic regression: the cOR is the probability of response of the patients who are carriers of the allele, with regard to non-carriers (reference groups).


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allele, which acts independently of HLA-DRB1 * 11 and could

also be associated with other alleles of HLA-DRB1 * such as 0401,

0407, 1303, and 1402. HLA-DRB1 * 1101 and DQB1 * 0301 have

been reproducibly shown to be involved in the spontaneous res-

olution of HCV infection in European populations ( 8 ). Diverse

studies have identifi ed signifi cant genetic associations with diff er-

ent HLA-DQB1 * 0301-bearing haplotypes, suggesting that HLA-

DQB1 * 0301 might be one of the most prominent factors in HCV

clearance ( 8 ).

At the end of 2009, three independent genome-wide association

studies reported that single-nucleotide polymorphisms near the

IL28B (IFN- λ 3) region were associated with treatment response

( 14,27,28 ). We found that the patients with the rs12979860 CC

genotype had a four times greater probability of SVR than did

those with the CT or TT genotype. But aft er stratifying for geno-

type, there was no signifi cant association between rs12979860 and

SVR among individuals infected with HCV genotype 1, indicating

that the prognostic value of the risk allele for treatment response

might be limited to individuals with diffi cult-to-treat HCV geno-

types. Th e same results were obtained by McCarthy et al. ( 29 )

and Rauch et al. ( 30 ), but in this case with genomic variants in

the rs8099917 locus.

Table 3 . Baseline characteristics of patients who are rs12979860 CC and rs12979860 CT / TT and relationship between non-SVR and SVR

rs12979860 CC ( n =142) rs12979860 CT / TT ( n =281)

Non-SVR, n =33

(23 % ) SVR, n =109

(77 % ) P a Non-SVR, n =151

(54 % ) SVR, n =130

(46 % ) P a

Age (years) b

≤ 40 9 (16) 46 (84) 0.1 40 (38) 66 (62) < 0.0001

> 40 24 (28) 63 (72) 111 (63) 64 (37)

Sex

Female 15 (28) 38 (72) 0.3 68 (55) 56 (45) 0.8

Male 18 (20) 71 (80) 83 (23) 74 (47)

Fibrosis stage ( n =267)

1 – 2 11(18) 50 (82) 0.2 69 (48) 75 (52) 0.2

3 – 4 7 (34) 15 (68) 24 (60) 16 (40)

Necroinfl ammatory grade ( n =259)

1 – 4 7 (16) 36 (84) 0.06 57 (48) 62 (52) 0.5

4 – 6 14 (33) 28 (67) 30 (54) 25 (45)

ALT (U / l)

≤ 40 8 (50) 8 (50) 0.02 12 (41) 17 (59) 0.2

> 40 26 (21) 100 (79) 137 (54) 115 (46)

AST (U / l)

≤ 40 8 (22) 29 (78) 0.8 46 (49) 48 (51) 0.3

> 40 26 (24) 79 (76) 105 (56) 82 (44)

GGT (U / l) b

≤ 37 21 (27) 57 (73) 0.8 54 (45) 67 (55) 0.006

> 37 15 (24) 49 (76) 99 (62) 61 (38)

Viral genotype b

2 or 3 4 (16) 21 (84) 0.4 5 (20) 20 (80) < 0.0001

1 or 4 29 (25) 88 (75) 146 (57) 110 (43)

Baseline viral load b (IU / ml)

≤ 600,000 5 (11) 41 (89) 0.01 34 (37) 59 (63) < 0.0001

> 600,000 28 (29) 68 (71) 117 (62) 71 (38)

ALT, alanine aminotransferase; AST, aspartate aminotransferase; GGT, γ -glutamyltransferase; SVR, sustained virological response. Values are absolute with percentages in parentheses. a Bivariate analysis: P value calculated by χ 2 test or Fisher’s test. b Mantel – Haenszel test: P ≤ 0.05.


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with the rs12979860 CC genotype are related to some of the

routes involved in the recognition of diff erent HLA specifi cities.

Th us, an IL28B genotype with higher levels of rs12979860 during

treatment may induce the maturation and activation of antigen-

presenting cells. Th ese antigen-presenting cells will present an

immunodominant peptide via HLA-DQB1 * 0301 to the CD4 +

Th 0 cells, which diff erentiates to CD4 + Th 1 anti-HCV. Further-

more, IL28B can induce HLA class I expression on hepatocytes

infected with HCV, and individuals with HLA-A * 0201 will more

effi ciently control HCV infection because they present a viral

peptide with a low rate of mutations that prevents escape from

anti-HCV cytotoxic CD8 + lymphocytes.

Th ese new genetic predictive factors will have to compete

with other viral predictors of response such as viral load or viral

Because of the growing importance of genetic host factors in

treatment outcome, the associations between the rs12979860

genotype and all the HLA alleles found in our population were

evaluated in SVR and non-SVR patients. It was found that only

two alleles were associated with the CC genotype and SVR:

HLA-DQB1 * 0301 and A * 0201. Th e HLA-DQB1 * 0301 allele

is independently associated with SVR, whereas patients with

HLA-A * 0201 require the presence of the CC polymorphism in

rs12979860 to increase the SVR rate. Although the genotypic rela-

tion between the HLA class II molecules and the IFN- λ ones is

well known and has recently been described ( 31 ), the phenotypic

relationship between the genotypes DQB1 * 0301 and rs12979860

CC with SVR are described in the present paper. We suggest that

at least some of the benefi cial eff ects of the response in patients

DQB1*0301 (+)rs12979860 CC

vs. DQB1*0301 (–)rs12979860 CT/TT

DQB1*0301 (–)rs12979860 CC

vs. DQB1*0301 (–)rs12979860 CT/TT

DQB1*0301 (+)rs12979860 CT/TT

vs. DQB1*0301 (–)rs12979860 CT/TT

A*0201 (+)rs12979860 CC

vs. A*0201 (–)rs12979860 CT/TT

A*0201 (–)rs12979860 CC

vs. A*0201 (–)rs12979860 CT/TT

A*0201 (+)rs12979860 CT/TT

vs. A*0201 (–)rs12979860 CT/TT

OR0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 2423

Figure 1 . Associations between rs12979860 polymorphism and HLA alleles evaluated in sustained viral response (SVR) and non-SVR patients. DQB1 * 0301( + ) and rs12979860 CC patients had a crude odds ratio (cOR) of 5.8 (95 % confi dence interval (CI): 2.3 – 14.8, P < 0.0001); DQB1 * 0301( − ) and rs12979860 CC patients had a cOR of 4.8 (95 % CI: 2.8 – 8, P < 0.0001); DQB1 * 0301( + ) and rs12979860 CT / TT patients had a cOR of 2.9 (95 % CI: 1.6 – 5.1, P < 0.0001); A * 0201( + ) and rs12979860 CC patients had a cOR of 8.6 (95 % CI: 3.2 – 23.4, P < 0.0001); A * 0201( − ) and rs12979860 CC patients had a cOR of 2.3 (95 % CI: 1.2 – 4.3, P = 0.013); A * 0201( + ) and rs12979860 CT / TT patients had a cOR of 1.5 (95 % CI: 0.8 – 2.5, P = 0.16). Each group of patients was compared with patients who were DQB1 * 0301( − ) or A * 0201( − ) and who had the rs12979860 CT / TT genotype (reference groups). cOR is the probability of SVR for each group of patients with respect to the reference group (patients with neither of the two alleles).

Genotype 2/3 vs. 1/4

Viral load ≤600,000 vs. > 600,000 IU/ml

Age ≤40 vs . >40 years old

DQB1*0301 (+) vs. DQB1*0301 (–)

rs12979860 CC vs. rs12979860 CT/TT

0 1 2 3 4 5 6 7 8

aOR

Figure 2 . Multivariate logistic regression: predictors of sustained viral response (SVR) to pegylated interferon / ribavirin therapy. Covariates of model: sex, age, alanine aminotransferase, γ -glutamyltransferase, viral genotype, viral load, carrier of the HLA-DQB1 * 0301 allele, and rs12979860 polymorphism. Final model: viral genotype (adjusted odds ratio (aOR) = 3.2, 95 % confi dence interval (CI): 1.4 – 7.2), age (aOR = 2.4, 95 % CI: 1.5 – 3.8), viral load (aOR = 2.2, 95 % CI: 1.4 – 3.6), carrier of DQB1 * 0301 (aOR = 2.08, 95 % CI: 1.2 – 3.5), and rs12979860 polymorphism (aOR = 4.3, 95 % CI: 2.6 – 7). aOR is the probability of SVR for each predictor with respect to the reference group to controlling for other variables. Hosmer and Lemeshow test: P = 0.8.


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genotype. Using ROC curve analysis, the most powerful predictive

pre-treatment variable of SVR was found to be rs12979860.

In conclusion, the HLA-DQB1 * 0301 allele and the rs12979860

genotype are signifi cant independent predictors of response to

pegIFN / RBV treatment in patients with chronic HCV infection.

Nevertheless, there is synergism between the HLA-DQB1 * 0301

and HLA-A * 0201 alleles with genotype rs12979860 CC, which

increases SVR valuation. Th ese results confi rm that studying

patients ’ immunogenetic factors can help in planning new, more

eff ective therapeutic strategies. Finally, the rs12979860 genotype

is the best predictor of response in patients with CHC treated

with pegIFN / RBV.

CONFLICT OF INTEREST Guarantor of the article : Javier Salmeron, MD.

Specifi c author contributions : Concept and study design:

Paloma Mu ñ oz de Rueda, Miguel Angel L ó pez-Nevot, and Javier

Salmeron; statistical analysis and interpretation; wrote and edited

the manuscript: Paloma Mu ñ oz de Rueda; consulted on manuscript

preparation: Miguel Angel L ó pez-Nevot and Javier Salmeron;

monitored the patients: Angeles Ruiz-Extremera, Ana Gila, and

Pablo Palomares; contributed patients to the study and monitored

these patients: Manuel Romero-G ó mez, Paloma Sanz-Cameno,

Ricardo Moreno-Otero, and Mois é s Diago; carried out laboratory

work: Jorge Casado, Antonia Mart í n-Casares, Rosa Quiles,

Esther-Jos é Pav ó n, and Jos é -Antonio Mu ñ oz; data acquisition

and creating the database: Á ngel Carazo and Josefa Le ó n. All

the authors reviewed the manuscript and approved the fi nal

version.

Financial support : Th is work was partially supported by the

Instituto de Salud Carlos III (Fondo de Investigaciones Sanitarias)

grant PI06 / 0939, Programa de estabilizaci ó n I3SNS, Conserjer í a

de Salud de la Junta de Andaluc í a PI387 / 05 and Ciberehd.

Potential competing interests: None.

Table 4 . Assessing probability of achieving SVR in patients with chronic hepatitis C

Age Viral load

Viral genotype DQ0301B1*

rs12979860 polymorphism

Probability of SVR ( % )

1 1 1 1 1 98

1 0 1 1 1 96

1 1 1 0 1 96

1 1 0 1 1 94

1 1 1 1 0 92

0 0 0 1 1 76

0 1 1 0 0 71

0 0 0 0 1 60

0 0 1 0 0 53

1 0 0 0 0 46

0 1 0 0 0 44

0 0 0 1 0 42

SVR, sustained virological response. Viral genotype 1 or 4=0, viral genotype 2 or 3=1; age > 40 years old=0, ≤ 40 years old=1; viral load > 600,000 IU / ml=0, ≤ 600,000 IU / ml=1; DQB1*0301( − )=0, DQB1*0301( + )=1; rs12979860 CT / TT=0, rs12979860 CC=1.

1.0

a b

0.8

IL28B

Mode 1: allcovariates

Model 2: withoutre12979860

Model 3:age+DQB1*0301+rs12979860

Model 4: age+viralload+viral genetic

Reference line

1.0

0.8

0.6

0.4

0.2

0.0

0.0 0.2 0.4

1-Specificity0.6 0.8 1.0

Viral genotype

Age

Viral load

DQB1*0301

Reference line

0.6

Sen

sitiv

ity

Sen

sitiv

ity

0.4

0.2

0.0

0.0 0.2 0.4 0.6

1-Specificity0.8 1.0

Figure 3 . Receiver operating characteristic (ROC) curve analysis of predictive factors of sustained viral response to pegylated interferon / ribavirin treatment in patients with chronic hepatitis C. ( a ) ROC curves for the variables independently: age (area under the curve (AUC) = 0.59), viral load (AUC = 0.59), viral genotype (AUC = 0.56), DQB1 * 0301 (AUC = 0.56), and rs12979860 polymorphism (AUC = 0.63). ( b ) ROC curves for four logistic models: model 1, age + viral load + viral genotype + carrier of DQB1 * 0301 + rs12979860 polymorphism (AUC = 0.76); model 2: age + viral load + viral genotype + carrier of DQB1 * 0301 (AUC = 0.69); model 3: age + carrier of DQB1 * 0301 + rs12979860 genotype (AUC = 0.72); model 4: age + viral genotype + viral load (AUC = 0.67). AUC model 1 vs. AUC model 2, P = 0.03; AUC model 3 vs. AUC model 4, P = 0.04.


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7 . Folgori A , Spada E , Pezzanera M et al. Early impairment of hepatitis C virus specifi c T cell proliferation during acute infection leads to failure of viral clearance . Gut 2006 ; 55 : 1012 – 9 .

8 . Hong X , Yu RB , Sun NX et al. Human leukocyte antigen class II DQB1*0301, DRB1*1101 alleles and spontaneous clearance of hepatitis C virus infection: a meta-analysis . World J Gastroenterol 2005 ; 11 : 7302 – 7 .

9 . Singh R , Kaul R , Kaul A et al. A comparative review of HLA associations with hepatitis B and C viral infections across global populations . World J Gastroenterol 2007 ; 13 : 1770 – 87 .

10 . Yee LJ . Host genetic determinants in hepatitis C virus infection . Genes Immun 2004 ; 5 : 237 – 45 .

11 . Rhodes SL , Erlich H , Im KA et al. Associations between the human MHC and sustained virologic response in the treatment of chronic hepatitis C virus infection . Genes Immun 2008 ; 9 : 328 – 33 .

12 . Yee LJ , Im K , Wahed AS et al. Polymorphism in the human major histocompatibility complex and early viral decline during treatment of chronic hepatitis C . Antimicrob Agents Chemother 2009 ; 53 : 615 – 21 .

13 . Dai CY , Chuang WL , Hsieh MY et al. Human leukocyte antigen alleles and the response to pegylated interferon/ribavirin therapy in chronic hepatitis C patients . Antiviral Res 2010 ; 85 : 396 – 402 .

14 . Ge D , Fellay J , Th ompson AJ et al. Genetic variation in IL28B predicts hepatitis C treatment-induced viral clearance . Nature 2009 ; 46 : 399 – 401 .

15 . Th omas DL , Th io CL , Martin MP et al. Genetic variation in IL28B and spontaneous clearance of hepatitis C virus . Nature 2009 ; 461 : 798 – 801 .

16 . Sheppard P , Kindsvogel W , Xu W et al. IL-28, IL-29 and their class II cytokine receptor IL-28R . Nat Immunol 2003 ; 4 : 63 – 8 .

17 . Marcello T , Grakoui A , Barba-Spaeth G et al. Interferons α and λ inhibit hepatitis C virus replication with distinct signal transduction and gene regulation kinetics . Gastroenterology 2006 ; 131 : 1887 – 98 .

18 . Dellgren C , Gad HH , Hamming OJ et al. Human interferon-l3 is a potent member of the type III interferon family . Genes Immun 2009 ; 10 : 125 – 31 .

19 . Caballero T , P é rez-Milena A , Masseroli M et al. Liver fi brosis assess-ment with semiquantitative indexes and image analysis quantifi cation in sustained-responder and non-responder interferon-treated patients with chronic hepatitis C . J Hepatol 2001 ; 34 : 740 – 7 .

20 . Shiff man ML , Suter F , Bacon BR et al. Peginterferon alfa-2a and ribavirin for 16 or 24 weeks in HCV genotype 2 or 3 . N Engl J Med 2007 ; 357 : 124 – 34 .

21 . Berg T , von Wagner M , Nasser S et al. Extended treatment duration for hepatitis C virus type 1: comparing 48 versus 72 weeks of peginterferon-alfa-2a plus ribavirin . Gastroenterology 2006 ; 130 : 1086 – 97 .

22 . Kamal SM , El Tawil AA , Nakano T et al. Peginterferon {alpha}-2b and ribavirin therapy in chronic hepatitis C genotype 4: impact of treatment duration and viral kinetics on sustained virological response . Gut 2005 ; 54 : 858 – 66 .

23 . Jacobson IM , Brown RS Jr , Freilich B et al. Peginterferon alfa-2b and weight-based or fl atdose ribavirin in chronic hepatitis C patients: a rand-omized trial . Hepatology 2007 ; 46 : 971 – 81 .

24 . Rosen HR , Weston SJ , Im K et al. Selective decrease in hepatitis C virus-specifi c immunity among African Americans and outcome of antiviral therapy . Hepatology 2007 ; 46 : 350 – 8 .

25 . Golden-Mason L , Klarquist J , Wahed AS et al. PD-1 expression is increased on immunocytes in chronic HCV and predicts failure of response to antiviral therapy: race-dependent diff erences . J Immunol 2008 ; 180 : 3637 – 41 .

26 . Lamonaca V , Missale G , Urbani S et al. Conserved hepatitis C virus sequences are highly immunogenic for CD4(+) T cells: implications for vaccine development . Hepatology 1999 ; 30 : 1088 – 98 .

27 . Suppiah V , Moldovan M , Ahlenstiel G et al. IL28B is associated with response to chronic hepatitis C interferon-alpha and ribavirin therapy . Nat Genet 2009 ; 41 : 1100 – 4 .

28 . Tanaka Y , Nishida N , Sugiyama M et al. Genome-wide association of IL28B with response to pegylated interferon-alpha and ribavirin therapy for chronic hepatitis C . Nat Genet 2009 ; 41 : 1105 – 9 .

29 . McCarthy JJ , Li JH , Th ompson A et al. Replicated association between an IL28B gene variant and a sustained response to pegylated interferon and ribavirin . Gastroenterology 2010 ; 138 : 2307 – 14 .

30 . Rauch A , Kutalik Z , Descombes P et al. Swiss Hepatitis C Cohort Study; Swiss HIV Cohort Study. Genetic variation in IL28B is associated with chronic hepatitis C and treatment failure: a genome-wide association study . Gastroenterology 2010 ; 138 : 1338 – 45 .

31 . Pietil ä TE , Latvala S , Osterlund P et al. Inhibition of dynamin-dependent endocytosis interferes with type III IFN expression in bacteria-infected human monocyte-derived DCs . J Leukoc Biol 2010 ; 88 : 665 – 74 .

Study Highlights

WHAT IS CURRENT KNOWLEDGE 3 Several viral factors, such as genotype, baseline viral load,

rapid virological response (4 weeks), early virological response (12 weeks), and amino-acid pattern in the viral genome, and several host factors, including age, sex, race, liver fi brosis stage, and obesity, have been associated with pegylated- α interferon / ribavirin therapy outcome.

3 Two HLA alleles are consistently associated with viral clearance and decreased disease severity of hepatitis C worldwide; these are HLA-DQB1 * 0301 and HLA-DRB1 * 11. The DRB1 * 11-DQB1 * 0301 haplotype is also associated with viral clearance and decreased disease severity of hepatitis C.

3 The HLA DR locus appears to be a prominent immuno-genetic factor infl uencing IFN treatment response.

3 The IL28B polymorphism is the fi rst genetic marker that predicts response to treatment for hepatic C virus genotype-1 with a genome-wide association study.

WHAT IS NEW HERE 3 A statistically signifi cant association of HLA class II allele

DQB1 * 0301 with sustained virological response (SVR) was found.

3 A statistically signifi cant association between the rs12979860 polymorphism and SVR was demonstrated in 428 patients of the same race (Caucasian) by PCR methods with single-nucleotide-polymorphism amplifi cation assays.

3 The HLA-DQB1 * 0301 allele and rs12979860 genotype are signifi cant independent predictors of response to pegylat-ed- α interferon / ribavirin (pegIFN / RBV) in patients with chronic HCV infection.

3 There is synergism between the HLA-DQB1 * 0301 and HLA-A * 0201 alleles with the rs12979860 CC genotype, which increases SVR valuation. The relationship between HLA alleles and IL28B has not previously been evaluated.

3 IL28B is the best predictor of SVR in patients with CHC treated with pegIFN / RBV, surpassing viral factors (viral genotype and viral load). No previous evaluation has been made of the viral and genetic factors, including IL28B, using receiver operating characteristic curves.

REFERENCES 1 . Poynard T , Yuen MF , Ratziu V et al. Viral hepatitis C . Lancet

2003 ; 362 : 2095 – 100 . 2 . Salmer ó n J , Mu ñ oz De Rueda P , Ruiz-Extremera A et al. Quasispecies as

predictive response factors for antiviral treatment in patients with chronic hepatitis C . Digest Dis Sci 2006 ; 51 : 960 – 7 .

3 . Salmer ó n J , Casado J , Mu ñ oz De Rueda P et al. Quasispecies as predic-tive factor of rapid, early and sustained virological responses in chronic hepatitis C, genotype-1, treated with peginterferon-ribavirin . J Clin Virol 2008 ; 41 : 264 – 9 .

4 . Mu ñ oz De Rueda P , Paton R , Casado J et al. Prospective studies of muta-tions in the E2-PePHD, NS5A-PKRBD, NS5A-ISDR and NS5A-V3 regions of hepatitis C virus genotype-1 and their relationship to peginterferon and ribavirin treatment response . J Virol 2008 ; 82 : 6644 – 53 .

5 . Kau A , Vermehren J , Sarrazin C . Treatment predictors of a sustained virologic response in hepatitis B and C . J Hepatol 2008 ; 49 : 634 – 51 .

6 . Feld JJ , Hoofnaglr JH . Mechanism of action of interferon and RBV in treatment of hepatitis C . Nature 2005 ; 436 : 967 – 72 .

Importance of Host Genetic Factors HLA and IL28B as Predictors of Response to Pegylated Interferon...

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