Wolbachia and the antifilarial properties of tetracycline. An untold story

The idea that tetracycline may have antifilarial properties was first propo sed in 1960. Data were subsequently published on the effects of tetracyclin e on the development and reproduction of Brugia pahangi in both the mosquit o and mammalian hosts. These studies were apparently ignored until recently . In 1998, it was suggested that the antifilarial properties of tetracyclin e may derive from the presence of the bacterial endosymbiont Wolbachia in f ilarial worms. In view of this renewed interest, we would like to highlight an old study on the prophylactic activity of tetracycline against three fi larial species. Although this work was performed at the begining of the sev enties, and presented at a congress in 1973, it has never been published. T his study showed that tetracycline had a prophylactic effect against infect ion of the mammalian host (the gerbil Meriones unguiculatus) with B. pahang i and Litomosoides sigmodontis. On the other hand, no significant prophylac tic effect of the drug was observed against Acanthocheilonema viteae in the same host. The new data on the distribution and phylogeny of Wolbachia end osymbionts 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 Wol bachia.