Isolation of Strongyloides venezuelensis from Rattus norvegicus in Kagoshima Prefecture.

Effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae

“…Infectivity of the L 3 was not different according to the culture methods although recovery rate of the MSL 3 and adult worms was slightly higher in those corresponding to FPC than those corresponding to NBC and FC. However, infectivity has been known to be significantly influenced by the inoculation routes; higher infection rate was resulted from subcutaneous and percutaneous inoculation than from oral administration of L 3 (Taira et al, 1994). The overall recovery rate of MSL 3 and adults in the present study are much higher than that observed in rats (Taira et al, 1994), but much lower than those in mice (Sato and Toma, 1990;Khan et al, 1993;Korenaga et al, 1995) and Mongolian gerbils .…”

“…In addition, this nematode does not cause sudden death even in massive infection in rats (Taira et al, 1995) as compared with another closely related species, Strongyloides ratti, which can cause sudden death in rats and Mongolian gerbils. The morphology of L 3 obtained from different conventional in vitro cultures as well as those of the in vivo derived adult worms have been reported previously (Little, 1966;Hasegawa et al, 1988;Taira et al, 1994). After primary infection with S. venezuelensis, the subsequent development to the parasitic adult stage in a single and/or concurrent infections with S. ratti, pulmonary and intestinal worm burdens, kinetics of egg outputs, persistence of infection and immunological responses have been reported in rats (Werthiem, 1970a(Werthiem, , 1970bCarter and Wilson, 1989), mice (Sato and Toma, 1990), Mongolian gerbils (Tsuji et al, 1993) and Syrian golden hamsters (Shi et al, 1994).…”

“…These findings suggest that growth and development of the L 3 are influenced not only by composition and/or methods of in vitro cultures but also by geographical and/or strain variations (Hasegawa et al, 1988). Irrespective of the culture methods, morphological dimensions with respect to body length of adults recovered from Fischer (F344) rats on day 7 PI were greater than those reported by Little (1966) and Taira et al (1994), but smaller than those reported by Wertheim (1970a) and Hasegawa et al (1988). This variation may be due to the Values represent the mean ± SD of five rats.…”

“…The reason for higher morphological development of adult worms corresponding to FPC is difficult to explain. Morphological dimensions with respect to body length of the L 3 recorded in NBC and FC except for FPC were observed smaller than those described for S. venezuelensis L 3 by several authors (Little, 1966;Wertheim, 1970a;Hasegawa et al, 1988;Taira et al, 1994). These findings suggest that growth and development of the L 3 are influenced not only by composition and/or methods of in vitro cultures but also by geographical and/or strain variations (Hasegawa et al, 1988).…”

“…The development of intestinal nematode from the free-living stage (e.g., L 3 stage) to the parasitic adult stage depends on several factors related to host (e.g., species, strain, age, sex and resistance) and parasite species (e.g., strain, infective dose and culture age of L 3 ) (Solomon and Haley, 1966;Carter and Wilson, 1989;Sato and Toma, 1990;Khan et al, 1993). Taira et al (1994) have demonstrated that the inoculation routes of S. venezuelensis L 3 significantly influence the worm burdens. Additionally, studies on morphological development and infectivity of free-living stage (e.g., L 3 ) and parasitic adult nematodes are considered useful in analysing the mode of action of anthelmintics and resistance thereto (Martin, 1997).…”