Wolbachia and the antifilarial properties of tetracycline.: An untold story

The idea that tetracycline may have antifilarial properties was first proposed in 1960. Data were subsequently published on the effects of tetracycline on the development and reproduction of Brugia pahangi in both the mosquito and mammalian hosts. These studies were apparently ignored until recently. In 1998, it was suggested that the antifilarial properties of tetracycline may derive from the presence of the bacterial endosymbiont Wolbachia in filarial worms. In view of this renewed interest, we would like to highlight an old study on the prophylactic activity of tetracycline against three filarial species. Although this work was performed at the begining of the seventies, and presented at a congress in 1973, it has never been published. This study showed that tetracycline had a prophylactic effect against infection of the mammalian host (the gerbil Meriones unguiculatus) with B. pahangi and Litomosoides sigmodontis. On the other hand, no significant prophylactic effect of the drug was observed against Acanthocheilonema viteae in the same host. The new data on the distribution and phylogeny of Wolbachia endosymbionts in filarial nematodes, showing that A. viteae is uninfected and that B. pahangi and L. sigmodontis are infected, suggest that the activity of tetracycline on the latter two species is related to the presence of Wolbachia.