Short report

Functional characterization of two newly identified Human Endogenous Retrovirus coding envelope genes

Sandra Blaise^2†, Nathalie de Parseval^1† and Thierry Heidmann^1*

• * Corresponding author: Thierry Heidmann heidmann@igr.fr

• † Equal contributors

Author Affiliations

¹ Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, UMR 8122 CNRS, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif Cedex, France

² Unité de Biologie des Rétrovirus, Département de Virologie, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France

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Retrovirology 2005, 2:19 doi:10.1186/1742-4690-2-19

Published: 14 March 2005

Abstract

A recent in silico search for coding sequences of retroviral origin present in the human genome has unraveled two new envelope genes that add to the 16 genes previously identified. A systematic search among the latter for a fusogenic activity had led to the identification of two bona fide genes, named syncytin-1 and syncytin-2, most probably co-opted by primate genomes for a placental function related to the formation of the syncytiotrophoblast by cell-cell fusion. Here, we show that one of the newly identified envelope gene, named envP(b), is fusogenic in an ex vivo assay, but that its expression – as quantified by real-time RT-PCR on a large panel of human tissues – is ubiquitous, albeit with a rather low value in most tissues. Conversely, the second envelope gene, named envV, discloses a placenta-specific expression, but is not fusogenic in any of the cells tested. Altogether, these results suggest that at least one of these env genes may play a role in placentation, but most probably through a process different from that of the two previously identified syncytins.