Parenteral and sexual transmission are not risk factors for acute hepatitis E infection in Hong Kong

Detection and characterization of hepatitis E virus genotype 3 in HIV-infected patients and blood donors from southern Brazil

BACKGROUND

Hepatitis E virus genotype 3 (HEV-3) infection usually causes self-limited acute hepatitis. In immunosuppressed patients, HEV-3 infection can rapidly progress to chronic hepatitis and cirrhosis. In southern Brazil, data on HEV seroprevalence are scarce.

METHODS

Testing for HEV RNA and antibodies (anti-HEV) was performed for 320 HIV-infected patients followed at the HIV/AIDS Service of the Federal University of Rio Grande between 2012 and 2013, as well as 281 blood donor samples obtained in 2015. Variables associated with anti-HEV positivity were assessed by multivariable logistic regression analysis.

RESULTS

HIV and blood donor groups showed similar HEV seroprevalence (6.7% and 7.1%, respectively). Risk factors associated with anti-HEV detection were older age, marital status, a higher number of sexual partners, poor sanitation, and alcohol use (HIV group), and living in a rural area (blood donors). HEV RNA was detected in eight serum samples from HIV-infected patients and in one blood donor, who was also positive for anti-HEV IgM and IgG.

CONCLUSIONS

The prevalence rates of HEV infection were comparable between HIV-seropositive patients who were not severely immunocompromised and blood donors. The blood donor's HEV isolate showed high similarity with swine HEV strains from Brazilian herds in the same region, thus indicating a potential risk of foodborne and parenteral transmission via blood transfusion.

Hepatitis E Vaccines

Hepatitis E accounts for the major part of enterally transmitted non-A, non-B hepatitis worldwide. Its agent, the hepatitis E virus (HEV), is a small, single-stranded RNA virus. Only one serotype of HEV is recognised. Infection results in protective immunity with long-lived neutralising antibodies. In developing countries with poor sanitary conditions and high population density, hepatitis E causes water-borne epidemics with substantial mortality rates in pregnant women. In addition, more than 50% of cases of acute hepatic failure and sporadic acute hepatitis are due to hepatitis E. The overall prevalence rates of antibodies to the HEV in populations native to these areas rarely exceed 25%. Hence, many individuals remain susceptible to hepatitis E infection, making hepatitis E an important public health concern. In this context, the development of an HEV vaccine is warranted. Because HEV does not grow adequately in cell cultures the development of a vaccine based on inactivated or attenuated whole-virus particles is not feasible. HEV vaccines currently under study are based on recombinant proteins derived from immunogenic parts of the HEV capsid gene. Other approaches such as DNA-based vaccines or transgenic tomatoes have also been developed. Several recombinant protein-based vaccines elicited neutralising antibodies and protective immunity in vaccinated non-human primates. One such vaccine has passed phase I trial and is currently under further evaluation in field trials. Even so, several questions remain to be answered before vaccination programmes could be implemented.