A tenth gene for the AIDS virus

Any biology textbook will tell you that the AIDS virus (HIV) has nine genes. The existence of a tenth gene, asp, was suggested in the late 1980s but remained a point of contention. However, this claim has recently been confirmed by scientists from the CNRS and the Institut Pasteur, who compared 23,000 sequences of HIV and SIV (the equivalent of HIV in non-human primates). They demonstrate that the asp gene only exists in the virus group responsible for the human pandemic and that its emergence coincided with the emergence of HIV-1 in humans in the early 20th century. Their findings, published this week in PNAS, also reveal a high selective pressure on the asp gene - in other words, the gene's presence within the viral genome is favored, meaning that it must be beneficial for the virus. All that remains now is to identify the gene's precise function. The scientists achieved this feat by applying a new bioinformatics approach. Research into this gene is complicated by the fact that its (overlapping) sequence is encoded on the antisense strand of the HIV-1 proviral genome and is entirely included in the region encompassed by the env gene coding for the viral envelope.

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