No abstract

Oka varicella vaccine has been used to confer active immunity to varicella-zoster virus (VZV) in healthy and immunocompromised hosts. Based on its attenuated nature, Oka varicella vaccine expressing human immunodeficiency virus (HIV) env antigen was constructed by inserting the HIVenv gene into the viral genome and its immunogenicity was assessed in guinea pigs. The HIVenv gene encoding 296-463 amino acids was inserted between the sequences of the hepatitis B surface antigen and the thymidine kinase gene of the cloned plasmid and the recombinant virus was isolated by cotransfection of the chimeric plasmid with viral DNA. Insertion of the HIVenv gene into the viral genome was confirmed by PCR and sequencing of the viral genome of the recombinant virus. The recombinant virus expressed 30k HIVenv fusion protein in its infected cells. In guinea pigs, immunization with the recombinant virus induced an antibody response to both the HIV antigen and the V3 peptide of gp120 as well as VZV gE:gI. Cell-mediated immunity to the HIV antigen and gE:gI was assessed by the cutaneous reaction representing delayed type hypersensitivity. Immunized guinea pigs responded well to both the HIV antigen and gE:gI. Thus the recombinant Oka varicella vaccine expressing the HIVenv antigen induced both a humoral and cell-mediated immunity to the HIV antigen similar to VZV as Oka varicella vaccine induces humoral and cell-mediated immunity to VZV in the vaccinees. This recombinant Oka varicella vaccine expressing the HIVenv antigen may be evaluated for its immunogenicity as one of the AIDS vaccine candidates.

Background: Crimean-Congo haemorrhagic fever (CCHF) is a viral tick-borne zoonosis that is widespread in Asia, Africa and Eastern Europe. CCHF was first recognized in South Africa in 1981 and is since then sporadically detected through passive laboratory surveillance.Methods & Materials: A retrospective epidemiological analysis including counts, outcomes, place and type of exposure were conducted for laboratory confirmed human CCHF cases in SA for the past 32 years . In order to investigate the genetic diversity of CCHF viruses isolated from human cases, conventional Sanger sequencing for a 536 base pair region of the S segment was performed for isolates collected from 2003 to 2013. For similiar sequences for CCHF reported from other countries and human cases SA prior to 2002, GENBANK derived sequences were included in the analysis.MEGA software was used to perform phylogenetic analysis of sequences using the neighbour-joining distance method and sequence divergence determined by calculating p distances between sequences.Results: A total of 193 human cases were laboratory confirmed for South Africa for the period 1981-2013. Most cases were reported from the semi-arid regions occupying the Northern Cape (n=44) and Free State (n=21) Provinces. Nearly two-thirds of cases were associated with tick exposures. The fatality rate over the 32 year period was 24% (n=46). Phylogenetic inference of CCHF virus isolates revealed six phylogenetic groups that partially related to the geographic origin of the viruses. Partial S segment sequencing of human isolates from South Africa collected over a three decade period revealed pair-wise differences ranging from 0.4-18% for nucleotide and 0-7% for deduced amino acids. All South African sequences clustered in one of three distinct phylogroups.Conclusion: Despite indication from previous studies of highseroprevalence in livestock in certian regions of South Africa, CCHF remains rarely reported in humans.Partial S segment sequencing revealed high level of sequence heterogeneity and phylogenetic inference indicated co-circulation of viruses belonging to three phylogroups. The grouping did not correlate with clinical severity of outcome.