Objective: Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent for Kaposi's sarcoma (KS), one of the most common cancers in Tanzania. We have investigated KSHV prevalence and factors associated with KSHV infection in Tanzania. Methods: This is a cross-sectional study of voluntary blood-donors from Dar es Salaam, Tanzania. Plasma was screened for KSHV, HIV-1, HBV, HCV and Treponema pallidum (syphilis). Associations between KSHV sero-status and risk factors were analyzed. Odds ratios (OR) and 95% confidence intervals (CI) are reported to evaluate risk factors of KSHV infection. All tests were 2-tailed, and P-values <0.05 were considered statistically significant. Results: The overall KSHV seroprevalence was 56.9%. Significantly increased risk of KSHV infection was detected in persons from the Lake and Central Zones (OR = 6.4, 95% CI = 1.6-25.3, P = 0.008 and OR = 5.7, 95% CI = 1.0-32.5, P = 0.048 respectively). A trend toward increased risk of KSHV infection with HIV-1 coinfection was not significant (OR = 2.8, 95% CI = 1.0-8.0, P = 0.06). Seroreactivity to T. pallidum was surprisingly high (14.9%). Conclusion:The prevalence of KSHV infection and syphilis was high among Tanzanian blood-donors. The most common transfusion-transmissible infections did not associate with KSHV infection. Regions of focal KSHV infection need further investigation for underappreciated risk factors.

Pigs were vaccinated by scarification or intramuscular injection with a swinepox virus-Aujeszky's disease (pseudorabies) recombinant (rSPV-AD) constructed by inserting the linked Aujeszky's disease virus genes coding for glycoproteins gp50 and gp63, attached to a vaccinia virus p7.5 promoter, into the thymidine kinase gene of swinepox virus. By 21 days after vaccination, 90 and 100 per cent of the animals vaccinated by scarification or intramuscular injection, respectively, had developed serum neutralising antibodies to Aujeszky's disease virus. Upon challenge with virulent virus, significantly fewer vaccinated pigs developed clinical Aujeszky's disease, nasal shedding of challenge virus was markedly reduced, and the vaccinated groups of pigs maintained or gained weight during the week after challenge whereas the unvaccinated control group lost weight. No transmission of rSPV-AD to in-contact controls was detected during the three weeks before challenge. In a second experiment, serum neutralising antibodies to Aujeszky's disease virus persisted for 150 days after the pigs were vaccinated with rSPV-AD by scarification or intramuscular injection and all the pigs showed an anamnestic response when they were revaccinated.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi’s sarcoma (KS), one of the most prevalent cancers of people living with HIV/AIDS in sub-Saharan Africa. The seroprevalence for KSHV is high in the region, and no prophylactic vaccine against the virus is available. In this study, we characterized the antigenic targets of KSHV-specific neutralizing antibodies (nAbs) in asymptomatic KSHV-infected individuals and KS patients with high nAbs titers. We quantified the extent to which various KSHV envelope glycoproteins (gB, ORF28, ORF68, gH, gL, gM, gN and gpK8.1) adsorbed/removed KSHV-specific nAbs from the plasma of infected individuals. Our study revealed that plasma from a majority of KSHV neutralizers recognizes multiple viral glycoproteins. Moreover, the breadth of nAbs responses against these viral glycoproteins varies among endemic KS, epidemic KS and asymptomatic KSHV-infected individuals. Importantly, among the KSHV glycoproteins, the gH/gL complex, but neither gH nor gL alone, showed the highest adsorption of KSHV-specific nAbs. This activity was detected in 80% of the KSHV-infected individuals regardless of their KS status. The findings suggest that the gH/gL complex is the predominant antigenic determinant of KSHV-specific nAbs. Therefore, gH/gL is a potential target for development of KSHV prophylactic vaccines.