TRICHOMONAS-VAGINALIS - REPEATED DNA TARGET FOR HIGHLY SENSITIVE AND SPECIFIC POLYMERASE CHAIN-REACTION DIAGNOSIS

Trichomoniasis is recognised as a major sexually transmitted disease ( STD) in the world and may act as an acquired immunodeficiency syndrome s (AIDS) co-factor by enhancing the transmission of human immunodefici ency virus (HIV). Diagnosis of Trichomonas vaginalis can be achieved b y several methods, but sensitive detection means are still lacking. In this study a 2000-bp repeated DNA fragment of T. vaginalis was cloned . Part of a conserved region of this insert was sequenced, two primers (TVK3 and TVK4) were chosen and a highly sensitive detection by polym erase chain reaction (PCR) was then developed for T. vaginalis. All st rains of T. vaginalis analysed with these primers gave the expected 35 0-bp fragment and a 450-bp additional fragment. Sequence analysis of t hese PCR amplification products revealed that the 450-bp fragment cont ained the 350-bp with a 100-bp insertion characterised by a TGG micros atellite. A second primer set, namely TVK3 and TVK7 (determined at the border of the insertion), yielded PCR products of expected sizes. Aft er amplification we were able to detect a single parasite. We also det ected T. vaginalis in vaginal fluids of patients with STD. There was n o reaction with human DNA or other infectious agents. It appears that the two set primers are highly specific of T. vaginalis and provide a useful tool for PCR diagnosis in asymptomatic and symptomatic patients especially among the HIV at risk individuals.