Do rhesus macaques have genital microbes resembling those seen in bacterial vaginosis?

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The composition of the lower genital tract microbiota in women is believed to affect the risk of sexually acquiring HIV. Because macaque genital microbiota might similarly affect vaginal infection with SIV, researchers identified the microbiota in 11 rhesus macaques using multitag pyrosequencing of the 16S rRNA gene.

The microbiota contained multiple types of bacteria, with a median of nine distinct bacterial taxa per macaque (range 3–16), each accounting for at least 1% of sequences. Frequently found taxa included Peptoniphilus, Sneathia, Porphyromonas, Mobiluncus, Atopobacter, Dialister, Thioreductor, Prevotella, and Streptococcus; many are also frequently found in women with bacterial vaginosis. Lactobacillus sequences, mostly L. johnsonii, were found in only four macaques and were not predominant in any (median 0% of sequences, range 0–39%).

To assess stability, all macaques were sampled again six months after the first sampling. The microbiota remained polymicrobial, with a median of 10 taxa (range 6–18). Microbial patterns remained similar in six macaques, changed substantially in two, and showed a mixed pattern in three. Significant sialidase enzyme activity, a marker of bacterial vaginosis in women, was detected in genital fluid from 9/11 macaques at the first sampling and 8/11 at the second.

The researchers concluded that macaque lower genital microbiota resembled a bacterial vaginosis-type microbiota in women and suggested that the microbiota of macaques in captivity promote rather than protect against vaginal SIV infection. They also suggested that macaques could serve as an animal model for studying some aspects of bacterial vaginosis.