Comparison of 33 epidemiologically distinct GBV-C/hepatitis G virus complete genome sequences suggests the existence of four major phylogenetic groupings that are equally divergent from the chimpanzee isolate GBV-C tro and have distinct geographical distributions. These four groupings are not consistently reproduced by analysis of the virus 5'-noncoding region (5'-NCR), or of individual genes or subgenomic fragments with the exception of the E2 gene as a whole or of 200-600 nucleotide fragments from its 3' half. This region is upstream of a proposed anti-sense reading frame and contains conserved potential RNA secondary structures that may be capable of directing the internal initiation of translation. Phylogenetic analysis of this region from certain South African isolates is consistent with previous analysis of the 5'-NCR suggesting that these belong to a fifth group. The geographical distribution of virus variants is consistent with a long evolutionary history that may parallel that of pre-historic human migrations, implying that the long-term evolution of this RNA virus is extremely slow.

The y interferon (,y-IFN) concentration and the adenosine deaminase (ADA) activity were evaluated in 30 patients with tuberculous peritonitis, 21 patients with ascites due to a malignant disorder, and 41 patients with cirrhosis. The y-IFN concentrations were significantly higher (p<0.0001) in tuberculous peritonitis patients (mean: 6-70 U/ml) than in the malignant (mean: 3.10 U/ml) and cirrhotic (mean: 3.08 U/ml) groups. Use of a cut off value of ¢3.2 U/mli gave the assay a sensitivity of93% (25 of 27), a specificity of 98% (54 of 55), positive (P+) and negative (P-) (Gut 1995; 36: 419-421)

The seroepidemiology of Helicobacter pylori infection was studied in 681 randomly selected Black children from newborn to 13 years of age (333 boys, mean age 8.05 years, and 348 girls, mean age 7.76 years) in KwaZulu/Natal, South Africa. H. pylori infection was identified serologically using an enzyme-linked immunosorbent assay to detect the presence of immunoglobulin G against H. pylori. Demographic information collected included age, gender, family income, overcrowding, educational level, and possession of domestic pets. The seroprevalence of H. pylori infection was compared to a known faecal-orally transmitted infection, hepatitis A virus (HAV); 66% of the children were seropositive for H. pylori. There was an age-specific increase in H. pylori infection, with more than 80% of children being infected by the age of 10 years. There was no significant difference (P = 0.338) in the seropositivity of H. pylori infection between boys (68%) and girls (64%), nor was there any significant difference in H. pylori infection related to pets, level of parents' education, crowding, and income, by either univariate or multivariate analysis. However, there was a significant association (P < 0.00001) between the seroprevalence of H. pylori and HAV infections, suggesting similar modes of transmission.

GB virus type C (GBV-C) is a common human flavivirus that has been associated with prolonged survival in HIV-positive individuals in several, though not all, epidemiological studies. There are five distinct GBV-C genotypes that are geographically localized, and it has been speculated that GBV-C genotypic differences may explain variable outcomes observed in different clinical studies. Expression of an 85 aa fragment of the GBV-C NS5A phosphoprotein (genotype 2) in a CD4+ T cell line (Jurkat) resulted in inhibition of HIV replication, mediated in part by decreased surface expression of the HIV coreceptor CXCR4 and upregulation of SDF-1. We expressed the NS5A protein from genotypes 1, 2, 3 and 5 in Jurkat cells, and demonstrated that all genotypes inhibited HIV replication. Further deletion mapping demonstrated that expression of a 30 aa fragment resulted in decreased CXCR4 surface expression, upregulation of SDF-1 and inhibition of HIV replication.

GB virus C (GBV-C) is a common, apparently nonpathogenic human flavivirus that has been associated in some studies with prolonged survival in human immunodeficiency virus (HIV)-positive persons. There are 5 distinct GBV-C genotypes localized to specific geographic regions, and genotype 2 has been previously shown to inhibit HIV replication in vitro in lymphocyte cultures. We identified GBV-C virus isolates representing genotypes 1, 2, and 5 in samples from South African blood donors. GBV-C genotype 1 and 5 isolates replicated in lymphocyte culture, inhibited X4 and R5 HIV-1 isolates, and induced RANTES and stromal-derived factor-1 chemokines in vitro. Thus, African GBV-C genotypes can inhibit HIV replication in vitro.