Genotype, phylogenetic analysis, and transmission pattern of occult hepatitis B virus (HBV) infection in families of asymptomatic HBsAg carriers

Abstract

Occult hepatitis B is defined by the presence of hepatitis B virus (HBV) DNA in the serum in absence of hepatitis B surface antigen (HBsAg). Studies were conducted to screen for occult HBV infection among family members of HBV carriers, incidentally detected positive for HBV infection with a view to assess the pattern of virus transmission among them. Nested PCR assay, employing independent sets of primers to surface and core genes, was used for detection of HBV DNA in serum samples from 28 index cases with asymptomatic HBV infection, and in serum samples from 72 HBsAg negative/anti-HBc positive family members. HBV DNA was detected in 15 HBsAg negative family members of 10 HBsAg positive index patients and was studied in detail. Direct sequencing of S gene region of 25 isolates (10 index cases and 15 contacts) and phylogenetic analysis with data base sequences revealed that genotypes A, C, and D and subtype adw2, adr, and ayw3 were present among them. Evidence of transmission from outside family sources was found in addition to intrafamilial transmission among individuals with occult infection. Mutations in the major hydrophilic loop (MHL) of the S gene region were also detected, including the 'vaccine escape' mutation G145R in three cases. Although majority of the occult infection was associated with low viral load, 3/ 15 (20%) cases were with higher viral load and potential infectivity. These cases are especially notable in diagnostic, blood banking, and transplantation services.

G1862T Mutation among Hepatitis B Virus-Infected Individuals: Association with Viral Genotypes and Disease Outcome in Kolkata, Eastern India

“…To avoid false-positive results, instructions to prevent cross-contaminations were strictly followed and the results were considered valid only when they were consistently obtained in duplicate [20] .…”

“…The HBV genotype was determined using the restriction fragment length polymorphism (RFLP) method as described by Lindh et al [19] and some of them especially those who belonged to genotype A were directly sequenced for the detection of subgenotypes (A1 or A2) as described previously [20] .…”

A study on sequence variations in pre‐S/surface, X and enhancer II/core promoter/precore regions of occult hepatitis B virus in non‐B, non‐C hepatocellular carcinoma patients in Taiwan

“…Occult HBV infection was detected even among family members of HBV carriers. 5 This so-called occult HBV infection has been identified by sensitive polymerase chain reaction (PCR) assays that detect low levels of HBV DNA in serum and/or liver tissue of HBsAg-negative subjects. [6][7][8] Since the early 1980s, several studies have reported the detection of HBV DNA in both tumorous and non-tumorous liver tissue of HBsAg-negative HCC patients.…”

The genetic backbone modulates the phenotype of hepatitis B surface antigen mutants

“…Interestingly, this was not invariant, as sample M31 (gC, sG145R), which also carried sI195T, did not influence the expression of the D2H5 epitope. Whilst sG145R has been reported to cause testing failures in genotype C (Datta et al, 2006;Hou et al, 2001), the addition of the concurrent sI195T, a distant codon change towards the C terminus, in sample M31 (gC) seems to have acted to preserve the HBsAg antigenicity despite a sG145R substitution. Sloan et al (2008) Major disruption of the a determinant was only seen rarely.…”