HDAg-L variants in covert hepatitis D and HBV occult infection among Amerindians of Argentina: new insights

DELFINO C; EIRIN ME; BERINI C; MALAN R; PEDROZO W; KRUPP R; BLEJER J; OUBIÑA J; MATHET V; BIGLIONE M

JOURNAL OF CLINICAL VIROLOGY : THE OFFICIAL PUBLICATION OF THE PAN AMERICAN SOCIETY FOR CLINICAL VIROLOGY.

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 54 p. 223 - 228

1386-6532

Background: Guidelines suggest that all HBsAg-positive patients should be tested for anti-HDV IgG antibodiesand to confirm active hepatitis D virus (HDV) infection by detection of HDV RNA by reversetranscriptase (RT) polymerase chain reaction (PCR).Objectives: The aim of this study was to determine the serological prevalence and molecular features ofHDV within an Amerindian community from Argentina exhibiting positivity for HBsAg and/or anti-HBctotal Ig.Study design: Forty-six plasma samples were tested for the detection of total anti-HDV antibodies byELISA. Concomitantly, a partial RNA region coding for the delta antigen (HDAg) was amplified by RTnestedPCR (RT-nPCR). In silica translation of DNA sequences into the amino acid (aa) sequence of HDAg-S(aa110–195) and HDAg-L (aa110–214) was performed.Results: Out of 46 HDV non-reactive samples by ELISA, 3 were HDV RNA positive by RT-nPCR. Thesesamples were anti-HBc-only positive, 2 of them identified as cases of occult hepatitis B infection (OBI).The 3 cases were HBeAg-negative and showed normal ALT/AST levels. All sequences were ascribed toHDV genotype 1, but exhibited nucleotide differences in HDAg-L coding region, among which, mutationsat codons 197 and 201 – reportedly known to promote in vitro an unsuitable interaction with HBsAg –were observed.Conclusions: These results provide evidence of covert HDV infection even among OBI, highlighting theneed to reevaluate the currently applied guidelines for HDV diagnostic algorithms, as well as to exploreif the observed mutations promote any effect on HDV pathogenesis.