title: Tetracycline inhibits development of the infective-stage larvae of filarial nematodes in vitro.
abstract: In recent years, studies have linked tetracycline treatment of filaria-infected animals with reduced adult worm burdens and decreased levels of microfilaremia. These observations are believed to be attributable to clearance of Wolbachia, intracellular rickettsial-like organisms found within filarial tissues. Although maximal worm reductions were observed when treatment was initiated early in infection, it is not known whether tetracycline inhibits development of infective-stage larvae. To address this issue, we studied the effect of tetracycline on three different species of filarial nematodes, Brugia malayi, Brugia pahangi, and Dirofilaria immitis, in a serumfree in vitro system supporting molting to the fourth larval stage. Tetracycline was capable of inhibiting L3 to L4 molting within a dosage range similar to that reported for susceptible rickettsial organisms. However, Wolbachia DNA could still be detected in nematodes from tetracycline-treated cultures. In addition, three other antibiotics with anti-rickettsial and anti-chlamydial activity (chloramphenicol, erythromycin, and ciprofloxacin) failed to inhibit L3 to L4 molting. Although tetracycline is capable of completely blocking molting of infective-stage larvae, it remains possible that this effect is due to pharmacological activities unrelated to its anti-rickettsial functions.
authors.affiliation: Department of Pathology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut, 06030-3105, USA.
authors.forename: H L
authors.initials: HL
authors.lastname: Smith
authors.forename: T V
authors.initials: TV
authors.lastname: Rajan
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017178:Brugia malayi / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D017179:Brugia pahangi / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004183:Dirofilaria immitis / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D007814:Larva / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D018978:Molting / Q000187:drug effects; D013752:Tetracycline / Q000494:pharmacology*; D020577:Wolbachia / Q000187:drug effects / Q000235:genetics / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D013752:Tetracycline