Bacterial offender in parasitic infection

Wolbachia bacteria are essential symbionts of filarial nematode parasites including Onchocerca volvulus — the causative agent of river blindness — but a role for the bacteria in human corneal pathology was unexpected. But, in March 8 Science, Amélie v. Saint André and colleagues from University Hospitals of Cleveland and Case Western Reserve University, Cleveland, USA show that species of endosymbiotic Wolbachia bacteria are actually involved in the pathogenesis of river blindness.

Saint André et al. used a murine model of corneal inflammation (keratitis) and injected soluble extracts of filarial nematodes into the corneal stroma. The corneas were subsequently examined by scanning confocal microscopy. They found that the predominant inflammatory response in the cornea was due to species of endosymbiotic Wolbachia bacteria and was dependent on expression of functional Toll-like receptor 4 (TLR4) on host cells (Science 2002, 295:1892-1895).

"The results presented here demonstrate that in...