Intracellular sequestration and transmission of HIV-1 in pregnancy

30-50% of infants born to HIV-1 seropositive mothers are infected. Although a vertical transmission of the virus to the foetus via trophoblastic cells and mechanisms of its access thereof have been made, one of several questions which remains is: how do HIV-1 infected cells of monocyte/macrophage (MM) lineage, i.e. Hofbauer cells, which facilitate viral transmission, avoid cytolytic destruction vs. that which occurs in infected CD4+ T-cells and serve as a reservoir for virus, wherein it replicates? Recent studies of transglutaminases (TGases), a ubiquitous family of Ca(2+)-dependent peptide ligases catalyzing the post-translational covalent cross-linking of proteins and incorporation of amines into proteins have revealed a unique spectrum of immunoregulatory (IR) properties. In consonance with these studies, the biochemical and immunohistochemical identification of decidual and placental TGases, and their associated IR properties, and earlier studies of uterine and placental macrophages, a hypothesis is purposed to account for the intracellular assembly and accumulation of HIV-1 within cells of MM lineage, and transmission therefrom, in pregnancy.