IL28B polymorphism and cytomegalovirus predict response to treatment in Egyptian HCV type 4 patients

Abstract

Aim: To test whether the status of positive cytomegalovirus (CMV) DNA detection adds to the predictive value of IL28B and to further categorize C/T allele carriers.

Methods: This study included 166 chronic hepatitis C (CHC) patients who received combined interferon and ribavirin therapy for 48 wk, 84 spontaneous hepatitis C virus (HCV) resolvers who were positive for IgG anti-HCV antibody and negative for HCV RNA, and 100 healthy subjects who were negative for both HCV antibodies and RNA as controls. Genomic DNA from peripheral blood was used for IL28B rs.12979860 single nucleotide polymorphism (SNP) and CMV DNA detection. A 139 bp fragment containing IL28B SNP was amplified in all subjects by polymerase chain reaction using a specifically designed primer. Then the IL28B rs.12979860 SNP was detected by restriction fragment length polymorphism (RFLP) genotyping. The presence of CMV DNA was tested by amplification of the gB1 gene using nested polymerase chain reaction. The role of CMV and IL28B rs.12979860 SNP genotypes in determining the response rate to combined interferon therapy and clinical status of patients were statistically analyzed.

Results: Current data showed that 67% of patients carrying the IL28B 12979860 C/C allele had a sustained viral response (SVR) while the genotypes C/T and TT were associated with lower SVR rates, 50% and 48%, respectively. SVR rates for the C/C allele were lower than other HCV genotypes and/or other populations. Genotype CC was associated with the response to interferon (P = 0.025). Genotype C/C was reduced from 48% in controls to 14% in CHC patients suggesting its protective role against progression to chronicity. The majority of spontaneously cleared subjects (86%) were C/C, confirming its protective role. The C/T allele was present in 71% of CHC patients compared with 38% of controls, so the use of IL28B SNP genotyping only in these patients may be of little value as a predictor of response. CMV reactivation occurred in 40% of CHC patients. Co-infection with CMV seriously diminished the response to interferon (IFN) therapy, with SVR rates in C/C genotypes 87.5% in CMV-negative patients and 12.5% in CMV-positive patients (P < 0.0001). SVR rates among C/T carriers were reduced to < 50% in patients with positive CMV DNA while the non-response rate doubled. These data indicate that a supplemental assay for CMV viremia adds to the prognostic value of IL28B genotyping.

Conclusion: The results suggest that both genetic (i.e., spontaneous) and therapeutic (IFN-based therapy) arms are complementary in the battle against HCV. CMV DNA testing may be of value to better predict the response to IFN, particularly in IL28B C/T carriers.

Keywords: Genetic polymorphisms; Hepatitis C; Human cytomegalovirus; Interleukin 28B; Spontaneous clearance.

Figure 1

Distribution of LI28B rs12979860 single nucleotide polymorphism alleles among a healthy Egyptian population, spontaneous clearance and chronic hepatitis C patients. A: A hundred healthy subjects representing ethnic backgrounds of the Egyptian population were typed for IL28B single nucleotide polymorphism (SNP) rs 12979860. The distribution of different allele frequencies is depicted as a pie chart; B: Eighty four patients with spontaneous clearance from hepatitis C virus (HCV) infection were typed for IL28B SNP rs 12979860. The distribution of different allele frequencies is depicted as a pie chart; C: A hundred and sixty six chronic hepatitis C (CHC) patients with low F scores (F0-F2) were typed for IL28B SNP rs 12979860. The distribution of different allele frequencies is depicted as a pie chart.

Figure 2

Rate of sustained viral response in IL28B variants. Among 166 chronic hepatitis C (CHC) patients treated with combined interferon (IFN) and ribavirin therapy, 80 patients did not achieve a sustained viral response (SVR) while 86 patients achieved a SVR. Among the 14% (24) of CHC patients bearing the C/C allele, 67% (16 patients) achieved a SVR, while the other two genotypes C/T and TT were associated with lower SVR rates; 50% and 48%, respectively. Genotype CC was associated with response to IFN (P = 0.025). HCV: Hepatitis C virus.

Figure 3

Association of cytomegalovirus reactivation with sustained viral response rates in C/C patients. The data shown clearly demonstrate that cytomegalovirus (CMV) reactivation has dramatically reduced the sustained viral response (SVR) rates in C/C genotypes as represented by a 12.5% SVR rate in CMV-positive patients compared with 87.5% in CMV-negative patients (P < 0.0001).

Figure 4

Sorting of C/T genotype according to association with cytomegalovirus infection. The sustained viral response (SVR) rates among C/T carriers, is reduced to < 50% of its value in cases where patients had cytomegalovirus (CMV) reactivation. On the other hand, the non-response rate is increased 2-fold in cases of CMV reactivation. HCV: Hepatitis C virus.