Community prevalence of hepatitis C viraemia: a polymerase chain reaction study

Dose-Dependent Hepacivirus Infection Reveals Linkage between Infectious Dose and Immune Response

More than 70 million people worldwide are still infected with the hepatitis C virus 30 years after its discovery, underscoring the need for a vaccine. To develop an effective prophylactic vaccine, detailed knowledge of the correlates of protection and an immunocompetent surrogate model are needed. In this study, we describe the minimum dose required for robust equine hepacivirus (EqHV) infection in equids and examined how this relates to duration of infection, seroconversion, and transcriptomic responses. To investigate mechanisms of hepaciviral persistence, immune response, and immune-mediated pathology, we inoculated eight EqHV naive horses with doses ranging from 1-2 copies to 1.3 × 106 RNA copies per inoculation. We characterized infection kinetics, pathology, and transcriptomic responses via next generation sequencing. The minimal infectious dose of EqHV in horses was estimated at 13 RNA copies, whereas 6 to 7 copies were insufficient to cause infection. Peak viremia did not correlate with infectious dose, while seroconversion and duration of infection appeared to be affected. Notably, seroconversion was undetectable in the low-dose infections within the surveillance period (40 to 50 days). In addition, transcriptomic analysis revealed a nearly dose-dependent effect, with greater immune activation and inflammatory response observed in high-dose infections than in low-dose infections. Interestingly, inoculation with 6-7 copies of RNA that did not result in productive infection, but was associated with a strong immune response, similar to that observed in the high-dose infections. IMPORTANCE We demonstrate that the EqHV dose of infection plays an important role for inducing immune responses, possibly linked to early clearance in high-dose and prolonged viremia in low-dose infections. In particular, pathways associated with innate and adaptive immune responses, as well as inflammatory responses, were more strongly upregulated in high-dose infections than in lower doses. Hence, inoculation with low doses may enable EqHV to evade strong immune responses in the early phase and therefore promote robust, long-lasting infection.

Prevalence of glomerulopathies in autopsies of patients infected with the hepatitis C virus

BACKGROUND

Several reports have shown hepatitis C virus (HCV) infection to be associated with various extrahepatic manifestations, including certain forms of glomerulopathy. The most frequently reported glomerulonephritis in patients infected with HCV is either membranoproliferative glomerulonephritis (MPGN) or cryoglobulinemic glomerulonephritis, and HCV has been directly implicated in their pathogenesis. Other investigators have reported a higher prevalence of HCV infection in patients with membranous glomerulonephritis, IgA nephropathy, and focal segmental glomerulosclerosis (FSGS). However, the prevalence of these glomerulopathies in patients infected with HCV is unknown.

METHODS

We conducted a 5-year retrospective review to determine prevalence of glomerulopathies in autopsies of patients infected with HCV. The renal histology on the autopsy reports was carefully reviewed for appropriate diagnosis of glomerulonephritis.

RESULTS

Of the 114 autopsies of patients infected with HCV during this period, the majority had been incarcerated and had state-mandated autopsies. The mean age of the patients was 46.8 +/- 10 years (+/- SD; range, 19-87). Of the 114 patients, 46 were white, 37 were African American, and 31 were Hispanic. The glomerulopathies seen were 3 MPGN, 2 membranous, 3 HIV-associated nephropathy, 1 idiopathic FSGS, 1 minimal change glomerulonephritis, and 3 diabetic nephropathy.

CONCLUSION

We conclude that although HCV is reported to be associated with membranoproliferative and membranous glomerulonephritis, their prevalence in these patients is not common.

Sexual transmission of hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) is the cause of almost all cases of parenterally transmitted non-A, non-B viral hepatitis (NANBH). HCV is an RNA virus, unrelated to the hepatitis viruses, A, B, D, or E; it was first identified in 1989. Although most infections become chronic, and it may lead to chronic liver disease, most patients with HCV infection are asymptomatic. The predominant modes of transmission are by blood, blood products, or other parenteral exposure, particularly injecting drug use. More contentious is the role of sexual transmission, although evidence for this was provided by studies of NANBH.

OBJECTIVE

This review considers the evidence for sexual transmission, and the types of studies used to estimate the rate of transmission and the factors that may influence it.

METHOD

A Medline search using the keywords hepatitis C, sex, transmission, and prevalence in MeSH and free text. References in papers were searched, and some unpublished data identified. References were further selected to illustrate different methodologies.

FINDINGS

Evidence for sexual transmission is provided by several types of study including prevalence studies in groups at risk of other STDs, investigation of cases identified from surveillance reports, and cross sectional and longitudinal partner studies. Many studies are limited by their small size, the sensitivity and specificity of early assays, lack of controls, or the difficulty of excluding other routes of transmission. One prospective cohort study reported an incidence of 12 per 1000 person years in the sexual partners of HCV infected patients. 1-3% of partners of HCV infected patients are found to be infected in cross sectional studies. Co-infection with HIV, duration of the relationship, or chronic liver disease may be independent cofactors increasing the risk of transmission. A meta-analysis of selected studies may be informative, and further larger prospective studies are required. There is a small but definite risk of sexual transmission of hepatitis C.

Analysis of hepatitis C virus-inoculated chimpanzees reveals unexpected clinical profiles

The clinical course of hepatitis C virus (HCV) infections in a chimpanzee cohort was examined to better characterize the outcome of this valuable animal model. Results of a cross-sectional study revealed that a low percentage (39%) of HCV-inoculated chimpanzees were viremic based on reverse transcription (RT-PCR) analysis. A correlation was observed between viremia and the presence of anti-HCV antibodies. The pattern of antibodies was dissimilar among viremic chimpanzees and chimpanzees that cleared the virus. Viremic chimpanzees had a higher prevalence of antibody reactivity to NS3, NS4, and NS5. Since an unexpectedly low percentage of chimpanzees were persistently infected with HCV, a longitudinal analysis of the virological profile of a small panel of HCV-infected chimpanzees was performed to determine the kinetics of viral clearance and loss of antibody. This study also revealed that a low percentage (33%) of HCV-inoculated chimpanzees were persistently viremic. Analysis of serial bleeds from six HCV-infected animals revealed four different clinical profiles. Viral clearance with either gradual or rapid loss of anti-HCV antibody was observed in four animals within 5 months postinoculation. A chronic-carrier profile characterized by persistent HCV RNA and anti-HCV antibody was observed in two animals. One of these chimpanzees was RT-PCR positive, antibody negative for 5 years and thus represented a silent carrier. If extrapolated to the human population, these data would imply that a significant percentage of unrecognized HCV infections may occur and that silent carriers may represent potentially infectious blood donors.

Tropical aspects of viral hepatitis. Hepatitis C

This paper reviews our current understanding of hepatitis C infection in tropical countries. Since its discovery in 1989, hepatitis C has been recognized as an important disease in many tropical countries. In Egypt the prevalence in some sections of the population may-exceed 20%. In most tropical areas, however, the epidemiology of hepatitis C infection is poorly defined. There are clear variations in the distribution of genotypes in different areas and this may be one of the factors which influence the natural history of infection in different regions of the world. Routes of infection in tropical countries are poorly defined, most carriers having no clear risk factors for infection. There is some speculation that inadequate sterilization of medical equipment may be a route of infection in some areas. A combination of factors may result in an increased risk of hepatocellular carcinoma developing in patients from the tropics infected with hepatitis C and the prognosis may be worse due to co-infection with hepatitis B and human immunodeficiency virus, both of which may lead to accelerated liver disease. Prospects for disease control are poor due to the difficulty of developing a vaccine to the virus.