Prenatal transmission of subtype C HIV-1 in Zimbabwe: HIV-1 RNA and DNA in maternal and cord blood

Strategies for screening cord blood for a public cord blood bank in high HIV prevalence regions

assay suggest that it could be used for the routine screening of CB units in conjunction with currently recommended maternal screening to reduce the risk of transplant transmissible infection.

HIV-1 Subtype C Mosaic Gag Expressed by BCG and MVA Elicits Persistent Effector T Cell Responses in a Prime-Boost Regimen in Mice

Over 90% of HIV/AIDS positive individuals in sub-Saharan Africa are infected with highly heterogeneous HIV-1 subtype C (HIV-1C) viruses. One of the best ways to reduce the burden of this disease is the development of an affordable and effective prophylactic vaccine. Mosaic immunogens are computationally designed to overcome the hurdle of HIV diversity by maximizing the expression of potential T cell epitopes. Mycobacterium bovis BCG ΔpanCD auxotroph and modified vaccinia Ankara (MVA) vaccines expressing HIV-1C mosaic Gag (Gag^M) were tested in a prime-boost regimen to demonstrate immunogenicity in a mouse study. The BCG-Gag^M vaccine was stable and persisted 11.5 weeks post vaccination in BALB/c mice. Priming with BCG-Gag^M and boosting with MVA-Gag^M elicited higher Gag-specific IFN-γ ELISPOT responses than the BCG-Gag^M only and MVA-Gag^M only homologous vaccination regimens. The heterologous vaccination also generated a more balanced and persistent CD4⁺ and CD8⁺ T cell Gag-specific IFN-γ ELISPOT response with a predominant effector memory phenotype. A Th1 bias was induced by the vaccines as determined by the predominant secretion of IFN-γ, TNF-α, and IL-2. This study shows that a low dose of MVA (10⁴ pfu) can effectively boost a BCG prime expressing the same mosaic immunogen, generating strong, cellular immune responses against Gag in mice. Our data warrants further evaluation in non-human primates. A low dose vaccine would be an advantage in the resource limited countries of sub-Saharan Africa and India (where the predominating virus is HIV-1 subtype C).

Antenatal HIV-1 RNA load and timing of mother to child transmission; a nested case-control study in a resource poor setting

Objective

To determine HIV-1 RNA load during the third trimester of pregnancy and evaluate its effect on in utero and intra-partum/postpartum transmissions in a breastfeeding population.

Design

A nested case-control study within a PMTCT cohort of antiretroviral therapy naive pregnant women and their infants.

Methods

A case was a mother who transmitted HIV-1 to her infant (transmitter) who was matched to one HIV-1 positive but non-transmitting mother (control).

Results

From a cohort of 691 pregnant women, 177 (25.6%) were HIV-1 positive at enrolment and from these 29 (23%) transmitted HIV-1 to their infants, 10 and 19 during in utero and intra-partum/postpartum respectively. Twenty-four mothers sero-converted after delivery and three transmitted HIV-1 to their infants. Each unit increase in log₁₀ viral load was associated with a 178 cells/mm³ and 0.2 g/dL decrease in TLC and hemoglobin levels, p = 0.048 and 0.021 respectively, and a 29% increase in the risk of transmission, p = 0.023. Intra-partum/postpartum transmitters had significantly higher mean viral load relative to their matched controls, p = 0.034.

Conclusion

Antenatal serum HIV-1 RNA load, TLC and hemoglobin levels were significantly associated with vertical transmission but this association was independent of transmission time. This finding supports the rationale for preventive strategies designed to reduce vertical transmission by lowering maternal viral load.

HIV/AIDS in Central Africa: pathogenesis, immunological and medical issues

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.