Maternal Fetal Transmission of Human Viruses and their Influence on Tumorigenesis (eBook)

The human foetus is separated from the maternal blood by the syncytiotrophoblast induced by endogeneous human retrovirus-encoded proteins. This barrier is a highly developed one, which suppors apical-basolateral transport of maternal idiotype and anti-idiotype IgG, IgG-virus complexes. The selective maternal-fetal transport of epitope- and paratope-bearing entities can influence the developping fetal immune system during pregnancy. The bidirectional maternal-fetal transfer of cells are of even more importance during pregnancy. Maternal cells with latent viruses transport viruses without impairment of fetal development. Cells with premaligant and malignant genetic transformation are also transported to the fetus. Fetal and neonatal tumours are initiated by such cells in spite of the antitumour potential of fetal organism. On the contary, the fetal cells repair maternal tissue injouries and survive in the organisms of the recipients for decades. These possess new consequences for the neonatal immunity and organ transplatation surgery.

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The maternal-fetal barrier represented by the syncytiotrophoblast was shown to be formed by epigenetically regulated endogeneous retroviruses. This barrier, however, possesses certain plasticity, it can be penetrated by nanoparticles of different size-classes, by methabolites, toxic substances by unidirectional or bidirectional transport enzyme systems, intercellular transport mechanisms and by maternal antibodies, immunocomplexes including virus-antibody complexes by specific receptor cascades. Bidirectional microchimerism perfuse the fetal organism with maternal cells and the maternal organism with fetal stem cells. Chromosomally integrated viruses (human herpesvirus 6, parvoviruses) latently infected lymphotropic herpesviruses and tumour cells can be present among the microchimeric cells which can survive in the recipient organisms in gradually decreasing number for several decades. Idiotypic interactions of T-B cells enable a generalization of single antigenic experiences and allow a transgenerational learning of the nascent immune system. The latter function is driven by maternal antibodies which represent a great deal of the mother's immunological knowledge of the external world of antigens. Therefore, maternal antibodies function as transgenerational messengers.