Study on risk factors for transplacental viral infections; effect of bacterial factors and double viral infections on virus replication in placenta and amniotic membranes.

Among risk factors for vertical transmission of HIV there are listed concomitant viral and bacterial infections. Therefore the influence on the viruses replication in human placenta and amniotic membrane cultures of double viral infection with two unrelated viruses - encephalomyocarditis (EMCV) and vesicular stomatitis virus (VSV) - was studied and compared with the replication of the viruses in single virus infection (EMCV or VSV) in the same organ cultures. Additionally effect of bacterial factors - lipopolysaccharide (LPS) Escherichia coli and sonicated Treponema pallidum antigens (Tpa) - on VSV replication in the same culture system was studied and compared with VSV replication in untreated explants. Two effects were observed in double-virus infected cultures and also in bacterial factors treated cultures: inhibition and stimulation of virus replication. The kind of effect in the both cases was dependent on the presence or absence of innate antiviral immunity. In virus-sensitive organs double infected or treated with LPS or Tpa, inhibition of virus titer (2-5 log TCID(50)/ml) was observed. In the organs expressing the innate immunity, stimulation (1-4 log TCID(50)/ml) of virus replication was noticed. Contribution of endogenous TNFalpha in both reactions (stimulation and inhibition) was confirmed using antibodies against the TNF. Copyright 2001 Harcourt Publishers Ltd.