A new subtype of hepatitis C virus genotype 3: analysis of available evidence

Variants in two gene members of the TNF ligand superfamily and hepatitis C virus chronic disease

AIM

To assess the possible correlation between single nucleotide polymorphisms (SNPs) of two members of TNF ligand superfamily genes, tumor necrosis factor-α (TNF-α) and lymphotoxin-α (LTA), and HCV chronic disease.

BACKGROUND

The causes of disease progression from hepatitis C virus (HCV) infection to chronic liver disease still remains unclear. Abnormal production of the cytokines alleged to be contributed to progression of the disease or viral persistence. Regulatory mechanisms that control the production of cytokines including genetic polymorphisms, especially at coding/regulatory regions of genes, may affect expression and secretion of the cytokines.

METHODS

In this case-control investigation, 258 individuals with serologically proven chronic HCV infection and 277 healthy controls were studied. Genotyping of rs1799964 variant of TNF-α and rs909253 intronic variant in LTA gene were performed. To confirm the results of genotyping, 10% of the specimens analyzed again by sequencing approach.

RESULTS

In this investigation, a significant association was observed between the TNF-α TC genotype and chronic HCV infection (P = 0.035). Moreover, the frequency of C allele was significantly different between control subjects in comparison with chronic HCV patients (P=0.02). On the other hand, no association was found between LTA gene polymorphism and susceptibility to chronic HCV infection.

CONCLUSION

These findings indicate that genetic variants like single nucleotide polymorphism in TNF-α rs1799964, could be a host factor associated with susceptibility to HCV chronic infection. However, further large scale investigations are needed to confirm this finding.

Lack of association between interleukin 28B gene polymorphisms (rs8099917G/T, rs12979860 C/T) and susceptibility to chronic hepatitis C virus infection, Tehran, Iran

AIM

Chronic Hepatitis C infection is a critical health problem worldwide, which caused by hepatitis C virus (HCV). Interleukin 28B (IL28B) is a determinant factor in disease progression and also susceptibility to chronic HCV infection.

BACKGROUND

The most significant aim of this study is to analyze the association between IL28B gene polymorphisms with susceptibility to chronic HCV infection in Iranian population.

METHODS

This study follows a case- control study design, in which, 288 patients with chronic hepatitis C and 250 healthy individuals were genotyped for IL28B polymorphisms (rs12979860 C/T and rs8099917 G/T). Studied population collected from Taleghani Haospital, Tehran. Genotyping of IL28B gene polymorphisms were performed using PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) method. 10 percent of the studied population was sequenced to validate the results.

RESULTS

rs8099917 G/T and rs12979860 C/T were differently distributed in hepatitis C patients and healthy controls in the female gender. TT, TG and GG genotypes distribution in the female gender were 56.7%, 39.8% and 4.5% in cases and 67%, 31.6% and 1.4% in controls (p=0.54). Also CC, CT and TT genotypes distribution were 31.8%, 61.4% and 6.8% in cases and 51.7%, 44.9% and 3.4% in controls (p=0.2). However, there was no significant difference in the allelic frequency and genotype distribution of rs12979860 C/T and rs8099917 T/G in both HCV patients with genotype 1a and 3a.

CONCLUSION

It seems that rs8099917 G/T polymorphism plays a significant role in susceptibility to chronic HCV infection in Iranian population. On the other hand, no association was found between rs12979860 C/T polymorphisms and chronic hepatitis C.

Expression of NS3/NS4A Proteins of Hepatitis C Virus in Huh7 Cells Following Engineering Its Eukaryotic Expression Vector

BACKGROUND

Although the development of novel therapeutic regimens to combat hepatitis C virus (HCV) infection have been speeded up with successful results, no efficient vaccines exist yet.

OBJECTIVES

This study aimed to construct a eukaryotic expression vector encoding nonstructural proteins, NS3/NS4A, of HCV genotype 3a, and evaluate its expression on Huh7 cell surface.

MATERIALS AND METHODS

The NS3/NS4A sequence was isolated from a patient with HCV-3a chronic infection, cloned into intermediate vector pTZ57R/T, and then used for engineering a mammalian expression vector, pDisplay, to direct the respective protein to the secretory pathway and anchor it to the plasma membrane. The expression of the protein in Huh7 cell, which was transiently transfected with the vector using Lipofectamine, was determined by immunocytochemical staining assay with fluorescein isothiocyanate (FITC)-conjugated antibodies to the HA/myc tags located besides the fusion fragment.

RESULTS

The results showed that the fragment was successfully amplified and cloned into a eukaryotic expression vector. Sequencing and enzyme digestion analysis confirmed the cloned gene completion and its correct position in the pDisply-NS3/NS4A plasmid. Immunocytochemical staining revealed that the target protein was expressed as a membrane-anchored protein in the Huh7 cells.

CONCLUSIONS

This study can serve as a fundamental experiment for the construction of a NS3/NS4A eukaryotic expression vector and its expression in mammalian cells. Further research is underway to evaluate the fragment immunogenicity in lab animal models.

Phylogenetic analysis of hepatitis C virus strains and risk factors associated with infection and viral subtypes among Iranian patients

Hepatitis C virus (HCV) has infected approximately 170 million people worldwide. While the seroprevalence of anti-HCV antibody among Iranian blood donors is 0.13%, HCV infection is prevalent in 59-80% of Iranian injecting drug users. One hundred seventy-eight anti-HCV positive patients were referred to the Gastroenterology Department at the Taleghani Hospital (Tehran, Iran) between June 2007 and June 2012. Out of 178 samples, 142 were positive for HCV-RNA. HCV subtypes were determined using phylogenetic analysis of the NS5B or 5'UTR/core regions. Of 142 viremic patients, 71 (50%) were infected with HCV subtype 1a, 43 (30.3%) with subtype 3a, 20 (14.1%) with subtype 1b, 3 (2.1%) with subtype 4d, 2 (1.4%) with subtype 4a, 1 (0.7%) with subtype 2b, and 1 (0.7%) with subtype 6a. Interestingly, genetic analysis of a sub-genomic fragment from one patient identified a non-subtypeable HCV genotype-3 strain. There was a significant association between HCV subtype and a history of injecting drug use (P = 0.003). Subtype 3a was predominant among patients with such a history. Injecting drug use was associated with younger age (P < 0.001). HCV subtype was also significantly associated with a history of upper gastrointestinal endoscopy (P = 0.02). Subtype 1a was more frequent among patients with such a history. In addition, history of upper gastrointestinal endoscopy was significantly associated with older age (P = 0.002). In conclusion, while HCV subtype 1a is predominant among infected Iranian individuals, subtype 3a is predominant among Iranian injecting drug users.