Application of a truncated ORF2 protein-based ELISA for diagnosis of hepatitis E in an endemic area.

Enterically transmitted waterborne hepatitis E (HE) caused due to hepatitis E virus (HEV) prevails as a significant public health problem endemic to India. Due to short-term viremia/fecal excretion and poor in vitro transmissibility of HEV, HE diagnosis depends on detection of specific IgM antibodies in serum. Present study evaluated performances of two in-house and six commercial IgM detection enzyme-linked immunosorbent assays (ELISAs) using sera collected from volunteers/acute hepatitis patients (n = 716).

Serum immunoglobulin G subclass responses in different phases of hepatitis E virus infection.

To investigate the specific immunoglobulin (Ig) G subclass responses in patients with hepatitis E virus (HEV) infection, an open reading frame 2 (ORF2) protein based enzyme-linked immunosorbant assay was used to measure antibody levels in sera obtained at different phases of infection. Sera were collected at 2-31 days and at 6 months after the onset of symptoms corresponding to the acute (n = 48, 100% IgM-positive) and convalescent (n = 17/48, 53% IgM-positive) phases of infection, respectively. IgM-negative sera from 61 individuals infected at least ≥6 months ago (prior exposure) were also tested.

Challenge studies in Rhesus monkeys immunized with candidate hepatitis E vaccines: DNA, DNA-prime-protein-boost and DNA-protein encapsulated in liposomes.

Complete ORF2 gene (1983bp) of hepatitis E virus (HEV) and the 450bp region within ORF2 containing neutralizing epitope (NE) cloned in pVAX1 and corresponding proteins expressed in baculovirus and prokaryotic systems respectively were evaluated as vaccine candidates. Two doses of liposome encapsulated DNA plus corresponding protein with both ORF2 and NE regions (Lipo-ORF2-DP and Lipo-NE-DP) showed 100% seroconversion and comparable anti-HEV titres in Swiss albino mice. These vaccine candidates were further evaluated as DNA, DNA-prime-protein-boost (DPPB) and liposome formulations in Rhesus monkeys.

Immunogenicity of candidate hepatitis E virus DNA vaccine expressing complete and truncated ORF2 in mice.

Hepatitis E virus (HEV) is a major cause of enterically transmitted acute hepatitis of adults in developing nations. Our present studies show that, the complete ORF2 gene (1-660 amino acids, a.a.