
<ArticleTitle>The <prot>bet</prot> gene of feline foamy virus is required for virus replication.</ArticleTitle>
<AbstractText>Foamy viruses (FV) are complex retroviruses with additional bel genes located between <prot>env</prot> and the 3' long-terminal repeat. The functions of the <prot>bel 2</prot> and <prot>bet</prot> genes are unknown and both are dispensable for replication of the prototypic human foamy virus in cell cultures. We examined the function(s) of <prot>bel 2</prot> and <prot>bet</prot> of the distantly related feline foamy virus (FFV) in the proviral context. Mutagenesis was used to alter the <prot>Bel 2</prot> and <prot>Bet</prot> or to abrogate their expression. The <prot>Bel 2</prot>/<prot>Bet</prot> mutants showed a 1000-fold reduced viral titer in feline kidney cells; in human 293T cells, viral titer was only about 10-fold reduced compared to wild-type FFV. In both cell types, the <prot>Bel 2</prot>/<prot>Bet</prot> mutations resulted in a reduced release of FFV particles. The results indicate that FFV <prot>Bet</prot> is required for efficient virus replication. The functions of the <prot>Bel 2</prot> and <prot>Bet</prot> proteins are discussed.</AbstractText>
