SOURCE:

Faculty: Health Sciences And Technology
Department: Medical Laboratory Science

CONTRIBUTORS:

Osuji I. Ahaneku
Ifeanyichukwu M. O.
Agbakoba N. R.

ABSTRACT:

Occult hepatitis B virus infection (OBI), characterized by detection of HBV DNA in the serum or tissues of subjects who have negative test for HBsAg has become a challenge to blood transfusion services. The aim of this study was to evaluate the status of occult HBV infection and other transfusion transmissible viral infections among healthy blood donors attending Nnamdi Azikiwe University Teaching Hospital (NAUTH) Nnewi and University of Abuja Teaching Hospital (UATH) Gwagwalada. Blood samples from 212 apparently healthy blood donors from the 2 hospitals (NAUTH- 104, UATH- 108) were re-tested for HBsAg, HIV and anti-HCV using 4th generation Enzyme Linked Immunosorbent Assay (ELISA). One hundred of the samples that tested negative to HBsAg, HIV and HCV were examined for the presence of HBV DNA by conventional polymerase chain reaction (PCR). Determination of HBV DNA load on some positive samples was done using Roche COBAS Real Time PCR. Gene sequencing was done using Sanger sequencing method to determine the HBV genotypes while the prevalence and pattern of HBV serological markers were determined using ELISA as well as HBV 5 Panel assay. Qualitative Reverse Transcriptase-PCR was used to confirm ELISA positive sera for HIV RNA and HCV RNA. Of the 100 blood donor samples that tested negative for HBV, HIV and HCV, 14 (14%) were confirmed as OBI, with 22% and 6% prevalence rates obtained at UATH, Abuja and NAUTH, Nnewi respectively (p=0.02). Of the 14 OBI samples, 12 (85.7%) were seropositive for HBV serologic markers. Among the HBV marker seropositives, 7 (58.3%) were positive for anti-HBs, 3 (25%) positive for anti-HBc, and 2 (16.7%) positive for both Anti-HBs and Anti-HBc. Three of 14 OBI blood donors (21.4%) were positive for anti-HBc IgM. None of the OBI samples was positive for HBeAg and anti-HBe markers. The mean viral load of the OBI samples (93±35 IU/mL) was statistically decreased in comparison to the overt HBV infected samples (33,176,108 ± 574,579 IU/mL) (p<0.0001). The DNA sequencing and phylogenetic analysis showed that all the OBI isolates belonged to Genotype E and 4 (80%) of 5 OBI isolates sequenced have gene sequences similar to HBV isolates from Sudan. The ELISA results gave 13.9%, 13.7% and 8.1% prevalence of HBV, HIV and HCV infections respectively among blood donors that tested negative by rapid test kits. Of the 28 samples positive for HBV by ELISA, 20 (71.4%) were positive for HBV DNA. Eight (36.4%) of 22 positive samples by HIV ELISA were positive for HIV RNA. Of the 14 samples of HCV ELISA positive, 4 (28.6%) were positive for HCV RNA. The prevalence of OBI among blood donors at NAUTH, Nnewi, and UATH, Abuja, was 14% with predominance of HBV genotype E while the prevalence of HBV, HIV and HCV infections among the blood donors that previously tested negative by rapid test kits were 13.9%, 13.7% and 8.1%, respectively. Most OBI blood donors were HBV serologic markers positive, with anti-HBc and anti-HBs seropositivity in high prevalence. It is recommended that blood donors be screened for HIV, HCV and HBsAg using ELISA 4th generation test kit to reduce transfusion transmissible viral infections. Screening of blood donors by Nucleic Acid Tests (NATs) should be introduced for routine screening of blood donors as it is highly sensitive and specific. The incorporation of HBV serologic markers particularly anti-HBc and anti-HBs in blood donor screening will reduce HBV transmission risk by occult blood donors.