Prevalence of aflatoxin B1 in liver biopsies of proven hepatocellular carcinoma in India determined by an in-house immunoperoxidase test

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death in the world. The incidence of HCC in India is reportedly low and varies from 0.2 to 1.9 %. Aflatoxins, secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus, are potent human carcinogens implicated in HCC. The prevalence of aflatoxin B1 (AFB1) as co-carcinogen was analysed using an in-house immunoperoxidase test in 31 liver biopsies and 7 liver-resection specimens from histopathologically proven HCC, and in 15 liver biopsies from cirrhosis patients (control group). Serum was tested for hepatitis B and C serological markers using commercial assays, and for AFB1 using an in-house ELISA with a sensitivity of approximately 1 ng ml(-1) for AFB1. In spite of positive AFB1 immunostaining in HCC cases, all serum specimens, from both HCC and the control groups, were AFB1-negative. There were 18 (58.1 %) HCC cases that revealed AFB1 in liver biopsies; 68.8 % (n=11) of non-B non-C hepatitis cases with HCC and 46.1 % (n=6) of the hepatitis B surface-antigen-positive subjects were positive for AFB1. Out of the two hepatitis B/hepatitis C virus co-infected cases, one was positive for AFB1. Of seven tumour-resection samples, six were positive for AFB1. Only one case revealed AFB1 in the non-tumour area of the resected material. Thus AFB1 staining was significantly associated with tumour tissue (P=0.03). Aflatoxins proved to have a significant association with HCC in this peninsular part of the subcontinent. The impact seems to be a cumulative process, as revealed by the AFB1 deposits in HCC liver tissue, even though the serum levels were undetectable.

Characterization of gamma2-human herpesvirus-8 glycoproteins gH and gL

The gamma2 human herpesvirus-8 (HHV-8) or Kaposi's sarcoma associated herpesvirus (KSHV) ORFs 22 and 47 are counterparts to glycoproteins gH and gL, respectively, that are conserved among the members of herpesviruses. To define HHV-8 gH and gL, rabbit polyclonal antibodies were raised against GST-gH and GST-gL fusion proteins. Anti-gL and anti-gH antibodies reacted with the surface of virus carrying BCBL-1 cells. Both antibodies immunoprecipitated the HHV-8 envelope associated 120 kDa and 41-42 kDa proteins. In transfected COS-1 cells, gH was expressed as an endo-H sensitive 110 kDa glycoprotein, which was absent on the surface of the cells. However, after co-transfection with gL, gH was detected as an endo-H resistant 120 kDa glycoprotein, and was expressed on the surface of the cells. Non-covalent complex formation between gH and gL was detected in the transfected COS-1 cells. Anti-gH and anti-gL antibodies neutralized HHV-8 infectivity in the absence of complement, individually and more efficiently together. However, virus binding to the target cells was not inhibited. These studies suggest that HHV-8 gL is required for gH processing and expression on the cell surface membranes, and gH/gL complex plays an important role in the post-binding step of HHV-8 infection.