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Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpes virus type 8 (HHV-8) is tightly linked to the development of Kaposi's sarcoma, primary effusion lymphoma (PEL) and some cases of multicentric Castleman's disease. Latency-associated nuclear antigen (LANA) is one of a limited number of KSHV genes consistently expressed in these diseases as well as in KSHV-infected cell lines derived from PEL, and has been shown to play crucial role in persistence of KSHV genomes in the infected cells. In this study, we explored the cellular factors that interact with LANA using yeast two-hybrid screening, and isolated a part of gene encoding human myeloid cell nuclear differentiation antigen (MNDA). MNDA is a hematopoietic interferon-inducible nuclear proteins with a HIN-200 family member with conserved 200-amino acid repeats. Immunoprecipitation assay revealed that LANA interacted with MNDA in a mammalian embryonic kidney cell line. MNDA transcript was undetectable in three PEL cell lines by reverse-transcription polymerase chain reaction, but it was induced by interferon alpha (IFNalpha). Moreover, LANA and MNDA were co-localized in the nuclei of MNDA-expressing PEL cells. Our results suggest that LANA interacts with MNDA in KSHV-infected cells exposed to IFNalpha. Such interaction may modulate IFN-mediated host defense activities.

The estimated worldwide prevalence of human immunodeficiency virus (HIV) infections topped 52.5 million in June 2003, a mere 20 years after the aetiological agent was shown to be a sexually transmissible virus with a predilection for CD4+ T lymphocytes. More than 22 million people have died of the acquired immunodeficiency syndrome (AIDS) and the condition has in one generation become the most devastating and persistent epidemics in recorded history. More than two thirds of the world total of HIV-infected people live in Sub-Saharan Africa. In Central and Southern Africa at least 20% of the adult population is infected. As these adults die, they leave increasing numbers of orphans. Life expectancy at birth declined by 10 years per decade since the late 1980s to 50 years in the late 1990s, and in Botswana it is estimated to be as low as 33 years by 2010. The epidemic is increasing unabated and prospects for a curative or protective vaccine remain remote. The impact on HIV in Africa has been so profound that it influences political, economic, agriculture/food security, social, education, defence, science and health considerations. The medical and in particular immunology communities in Central Africa have the invidious challenge of on the one hand diagnosing the condition, monitoring its impact and contributing to treatment and management efforts. The science and clinical practice of immunology is challenged to find answers to the epidemic, perhaps including a vaccine. In this review we address the peculiarities of the HIV epidemic in Africa, its epidemiology and immunopathogenesis. We address the effect of the epidemic on individual patients, in their homes, workplaces and the knock-on effects on families and friends of the infected. Respective specialists discuss special groups (women, children) that are predominantly seen in Africa. We also discuss the impact of the epidemic on the clinical practice of medicine in general and challenges faced in the introduction of antiretroviral medicines. We also discuss options available for the diagnosis, treatment and monitoring of HIV-infected patients in this region., (Copyright 2003 S. Karger AG, Basel)

Background and Objectives: Sexual behavior following voluntary HIV counseling and testing (VCT) is described in 963 cohabiting heterosexual couples with one HIV positive and one HIV negative partner ('discordant couples'). Biological markers were used to assess the validity of self-report., Methods: Couples were recruited from a same-day VCT center in Lusaka, Zambia. Sexual exposures with and without condoms were recorded at 3-monthly intervals. Sperm detected on vaginal smears, pregnancy, and sexually transmitted diseases (STD) including HIV, gonorrhea, syphilis, and Trichomonas vaginalis were assessed., Results: Less than 3% of couples reported current condom use prior to VCT. In the year after VCT, > 80% of reported acts of intercourse in discordant couples included condom use. Reporting 100% condom use was associated with 39-70% reductions in biological markers; however most intervals with reported unprotected sex were negative for all biological markers. Under-reporting was common: 50% of sperm and 32% of pregnancies and HIV transmissions were detected when couples had reported always using condoms. Positive laboratory tests for STD and reported extramarital sex were relatively infrequent. DNA sequencing confirmed that 87% of new HIV infections were acquired from the spouse., Conclusions: Joint VCT prompted sustained but imperfect condom use in HIV discordant couples. Biological markers were insensitive but provided evidence for a significant under-reporting of unprotected sex. Strategies that encourage truthful reporting of sexual behavior and sensitive biological markers of exposure are urgently needed. The impact of prevention programs should be assessed with both behavioral and biological measures.

The ability of HIV-1 to evolve resistance to antiretroviral drugs leads to treatment failure. By nucleotide sequencing of HIV-1 subtype B isolates, amino acids responsible for drug resistance have been identified. Less information is available, however, on the extent and distribution of these amino acids in HIV-1 nonsubtype B viruses circulating mainly in developing countries. More HIV-infected patients in the developing world are now using antiretroviral drugs, and hence there is a need to monitor drug resistance mutations in HIV-1 non-subtype B viruses. This study examines the prevalence of drug resistance mutations in 28 antiretroviral drug-naive HIV-1-infected Zambians. HIV-1 proviral DNA was extracted from peripheral blood mononuclear cells. The region encompassing gag p17 to env C2-V3-C3 was amplified by the polymerase chain reaction followed by direct sequencing. Sequence analyses for drug resistance-associated mutations in th e protease and reverse transcriptase genes, and HIV-1 subtyping, were done. Overall, 92.8% of the generated sequences were HIV-1 subtype C. The generated sequences revealed only secondary associated, but no primary, drug-resistance mutations The most frequent secondary mutations in the protease and RT genes were, respectively, I93L(91.7%), L89M (79.2%), M3611V (79%, 4.2%), and R211K (70.8%), S48T (62.5%). The atypical residues M41N (3.6%) and D67A (3.6%) were detected in the RT gene. This study reveals many naturally occurring polymorphisms in HIV-1 subtype C isolates from antiretroviral drug-naive individuals. Such polymorphisms could lead to rapid treatment failure and development of drug-resistant HIV-1 mutants in individuals undergoing antiretroviral therapy.

Polymerase chain reaction (PCR) using Pneumocystis carinii-specific primers pAZ 102-H(5'-GTGTACGTTGCAAAGTACTC-3') and pAZ 102-E(5'-GATGGCTGTTTCCAAGCCCA-3') was performed on oropharyngeal washes obtained at autopsy from 22 AIDS children with histologically confirmed P. carinii pneumonia (PCP), and 48 control AIDS children who died from other infections. Fifteen of 22 (68%) PCP samples and none of 48 (0%) control samples had detectable P. carinii DNA (sensitivity 68%; specificity 100%; positive predictive value 100%; negative predictive value 87%). This method requires further validation in clinical practice.

Most human immunodeficiency virus type 1 (HIV-1) transmissions in sub-Saharan Africa are believed to occur between married adults who are discordant for their HIV-1 infection status; however, no studies to date have investigated the molecular epidemiology of such transmission events. Here we report the genetic characterization of HIV-1 strains from 149 transmission pairs that were identified prospectively in a cohort of discordant couples in Lusaka, Zambia. Subgenomic gag, gp120, gp41, and/or long terminal repeat regions were amplified by PCR analysis of uncultured blood samples from both partners and sequenced without interim cloning. Pairwise genetic distances were calculated for the regions analyzed and compared to those of subtype-specific reference sequences as well as local controls. Sequence relationships were also examined by phylogenetic tree analysis. By these approaches, epidemiological linkage was established for the majority of transmission pairs. Viruses from 129 of the 149 couples (87%) were very closely related and clustered together in phylogenetic trees in a statistically highly significant manner. In contrast, viruses from 20 of the 149 couples (13%) were only distantly related in two independent genomic regions, thus ruling out transmission between the two partners. The great majority (95%) of transmitted viruses were of subtype C origin, although representatives of subtypes A, D, G, and J were also identified. There was no evidence for extensive transmission networks within the cohort, although two phylogenetic subclusters of viruses infecting two couples each were identified. Taken together, these data indicate that molecular epidemiological analyses of presumed transmission pairs are both feasible and required to determine behavioral, virological, and immunological correlates of heterosexual transmission in sub-Saharan Africa with a high level of accuracy.

Little is presently known about the specific routes of transmission of Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus-8 (HHV-8). To investigate whether this agent might be transmitted vertically from mother to infant, we conducted a study on 89 KSHV seropositive mothers and their newborn infants. Thirteen mothers (14.6%) had KSHV DNA detected in their peripheral blood mononuclear cells (PBMC). Two of 89 samples drawn at birth from infants born to KSHV seropositive mothers had KSHV DNA detectable within their PBMC. These findings suggest that KSHV can be transmitted perinatally, but infrequently. Other routes of transmission such as horizontal transmission remain the most likely means of KSHV transmission., (Copyright 2001 Wiley-Liss, Inc.)

More than 80% of the world's HIV-infected adults live in sub-Saharan Africa, where heterosexual transmission is the predominant mode of spread. The virologic and immunologic correlates of female-to-male (FTM) and male-to-female (MTF) transmission are not well understood. A total of 1022 heterosexual couples with discordant HIV-1 serology results (one partner HIV infected, the other HIV uninfected) were enrolled in a prospective study in Lusaka, Zambia and monitored at 3-month intervals. A nested case-control design was used to compare 109 transmitters and 208 nontransmitting controls with respect to plasma HIV-1 RNA (viral load, VL), virus isolation, and CD4(+) cell levels. Median plasma VL was significantly higher in transmitters than nontransmitters (123,507 vs. 51,310 copies/ml, p < 0.001). In stratified multivariate Cox regression analyses, the risk ratio (RR) for FTM transmission was 7.6 (95% CI: 2.3, 25.5) for VL > or = 100,000 copies/ml and 4.1 (95% CI: 1.2, 14.1) for VL between 10,000 and 100,000 copies/ml compared with the reference group of <10,000 copies/ml. Corresponding RRs for MTF transmission were 2.1 and 1.2, respectively, with 95% CI both bounding 1. Only 3 of 41 (7%) female transmitters had VL < 10,000 copies/ml compared with 32 of 93 (34%) of female nontransmitters (p < 0.001). The transmission rate within couples was 7.7/100 person-years and did not differ from FTM (61/862 person-years) and MTF (81/978 person-years) transmission. We conclude that the association between increasing plasma viral load was strong for female to male transmission, but was only weakly predictive of male to female transmission in Zambian heterosexual couples. FTM and MTF transmission rates were similar. These data suggest gender-specific differences in the biology of heterosexual transmission.

Molecular epidemiology of HIV-1 in Zambia was investigated by direct sequencing of PCR products from samples collected from antenatal attendees in Lusaka, Zambia. One hundred and forty samples were initially screened for HIV, using antibody assays. Thirty-three (23.6%) samples were HIV-1 positive. Sequences of the HIV-1 env gp120 region were obtained from 28 of 33 (85%) HIV-1-positive samples. Twenty-six of the 28 sequences were HIV-1 env subtype C-like as previously reported. However, one HIV-1 env subtype D-like virus and one HIV-1 env subtype G-like virus were identified. This is the first time that these two HIV-1 env subtype viruses have been identified in Zambia, suggesting that more subtypes could be in existence.

The prevalence of hepatitis B virus (HBV) markers was studied in pregnant women attending antenatal clinics in Zambia. A total of 2,098 pregnant women were recruited into the study at three urban health centres in Lusaka, the capital city and four district hospitals in rural areas of different provinces of Zambia. The overall prevalence of HBsAg was 6.5% (137/2,098), and HBeAg was present in 16.1% (22/137) of those positive for HBsAg. Antibody positive rate (HBsAb and/or HBcAb) was 51.3% in randomly selected HBsAg negative samples. HBsAg positive rate varied between 3.3% and 13.6% in each study sites. Prevalence for both HBsAg and antibodies to HBV were significantly higher in rural areas (district hospitals) than in urban areas (urban health centres in Lusaka). These data show that although HBV is endemic in Zambia, the prevalence varies from region to region.

There was an outbreak of "a mysterious disease" at a Zambian school dormitory in September, 1993. Investigation with questionnaire and collection of throat swab specimens for virus isolation were carried out on 46 patients to identify the causative agent. In this outbreak, most of the patients showed similar symptoms such as fever, headache, sore throat, cough, etc. The disease had spread to all dormitories within a couple of days after the onset of the first cases. From these patients, 13 influenza viruses A/H3N2 were isolated on MDCK cell line. This was a first ever confirmed outbreak of influenza virus infection in Zambia.