RESUMO
Mammalian C-type retroviruses are inactivated by human serum, following triggering of the classical complement cascade. This may have inhibited transmission to humans of C-type oncoviruses from other mammals. Indeed, the retroviruses human immunodeficiency virus and human T-cell leukaemia virus are resistant to human complement. Antibody-independent activation of human C1q, the first component of the classical pathway, by retroviral envelope proteins has been described. However, retroviruses produced from human cells are resistant to inactivation by human complement and human serum is known to contain antibodies directed against carbohydrates on retroviral envelopes. Gal(alpha 1-3)Gal terminal carbohydrates are expressed by most mammals but are absent in humans, which lack a functional (alpha 1-3)galactosyltransferase gene. Here, we demonstrate that anti-Gal(alpha 1-3)Gal antibodies in human serum inactivate retroviruses produced from animal cells. Expression of porcine (alpha 1-3)galactosyltransferase in human cells renders the cells and the retroviruses they produce sensitive to human serum.
Assuntos
Galactose/metabolismo , Galactosiltransferases/metabolismo , Retroviridae/metabolismo , Células 3T3 , Animais , Anticorpos/imunologia , Sequência de Carboidratos , Linhagem Celular , Cães , Galactosiltransferases/antagonistas & inibidores , Galactosiltransferases/sangue , Humanos , Vírus da Leucemia Murina/metabolismo , Camundongos , Dados de Sequência Molecular , SuínosAssuntos
Mapeamento Cromossômico , Endotélio Vascular/enzimologia , Galactosiltransferases/biossíntese , Galactosiltransferases/genética , Expressão Gênica/efeitos dos fármacos , Oligonucleotídeos Antissenso/farmacologia , Suínos/genética , Animais , Antígenos Heterófilos/biossíntese , Antígenos Heterófilos/genética , Células Cultivadas , Clonagem Molecular , DNA Complementar , Endotélio Vascular/citologia , Citometria de Fluxo , Biblioteca Gênica , Hibridização In Situ , Linfócitos/fisiologia , Reação em Cadeia da Polimerase , Baço/enzimologiaRESUMO
Human serum contains natural antibodies (NAb), which can bind to endothelial cell surface antigens of other mammals. This is believed to be the major initiating event in the process of hyperacute rejection of pig to primate xenografts. Recent work has implicated galactosyl alpha 1,3 galactosyl beta 1,4 N-acetyl-glucosaminyl carbohydrate epitopes, on the surface of pig endothelial cells, as a major target of human natural antibodies. This epitope is made by a specific galactosyltransferase (alpha 1,3 GT) present in pigs but not in higher primates. We have now cloned and sequenced a full-length pig alpha 1,3 GT cDNA. The predicted 371 amino acid protein sequence shares 85% and 76% identity with previously characterized cattle and mouse alpha 1,3 GT protein sequences, respectively. By using fluorescence and isotopic in situ hybridization, the GGTA1 gene was mapped to the region q2.10-q2.11 of pig chromosome 1, providing further evidence of homology between the subterminal region of pig chromosome 1q and human chromosome 9q, which harbors the locus encoding the AB0 blood group system as well as a human pseudogene homologous to the pig GGTA1 gene.
