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

Abstract

Abstract:The effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae (L 3 ) to rats were investigated. A significantly higher body length was observed in L 3 from filter paper culture (597.3 ± 32.2 µm) than those in fecal (509.9 ± 35.0 µm) and nutrient broth culture (503.3 ± 31.0 µm) (P<0.05). Larval infectivity was assessed by exposing rats to 1,000 L 3 from each culture and worms were recovered from the lungs and small intestines. Recovery rate of these worms did not show any significant difference. A significantly greater body length of adults was recorded in those corresponding to the L 3 harvested from filter paper (2,777.5 ± 204.4 µm) and nutrient broth culture (2,732.5 ± 169.8 µm) than those corresponding to the L 3 obtained from fecal culture (2,600.5 ± 172.4 µm) (P<0.05). Although worm fecundity and EPG counts differed among culture methods but worm burdens and course of infection did not. These findings suggest that the methods of cultures have a significant effect on the morphological development of the larvae to the L 3 stage, but do not influence the infectivity to rats.

Persistent infection with Strongyloides venezuelensis in the Mongolian gerbil (Meriones unguiculatus)

“…The morphology of adult S. venezuelensis worms regularly showed tendencies of increasing dimensions with respect to length and width of the body among those recovered after death of the infected gerbils. The morphological changes of S. venezuelensis in the gerbil host appeared to be much greater than those reported in normal rats (Wertheim, 1970;Hasegawa et al, 1988;Sato & Toma, 1990;Islam et al, 1999), indicating that gerbil hosts favored extended development of S. venezuelensis worms in the small intestine. The fecundity of these worms was also found to be higher than those recovered from mice (5.5 ± 0.9) by Sato & Toma (1990) but lower than those in rats (7.2 ± 1.9) (Islam et al, 1999).…”

“…The morphological changes of S. venezuelensis in the gerbil host appeared to be much greater than those reported in normal rats (Wertheim, 1970;Hasegawa et al, 1988;Sato & Toma, 1990;Islam et al, 1999), indicating that gerbil hosts favored extended development of S. venezuelensis worms in the small intestine. The fecundity of these worms was also found to be higher than those recovered from mice (5.5 ± 0.9) by Sato & Toma (1990) but lower than those in rats (7.2 ± 1.9) (Islam et al, 1999). These findings indicate that the Mongolian gerbil is a suitable model for Strongyloides species, particularly for S. venezuelensis, which has poor immunogenicity.…”

“…Faecal egg output in terms of eggs per gram (EPG) of faeces was examined starting on day 3 PI and subsequently on the 5 th , 7 th , 9 th , 21 st , 35 th , 105 th , and 570 th day PI. EPG was determined on freshly passed faeces according to the methods of Islam et al (1999). Briefly, the individual gerbil was placed in a 100 ml beaker and allowed a few minutes to discharge faeces.…”

“…Adult worm populations were recovered from the small intestines of five gerbils sacrificed at various time intervals (i.e., 7 th , 21 st , 35 th , 105 th and 570 th day) following the methods of Islam et al (1999). Briefly, the entire small intestine of each sacrificed gerbil was dissected longitudinally and incubated at 37°C for five hours in Baermann's device.…”

Strongyloides ratti and S. venezuelensis – rodent models of Strongyloides infection

“…The conditions in which the free-living stages are grown and the within-host conditions can affect the morphology of the free-living and parasitic generation of Strongyloides spp., respectively (Speare, 1989), and this has been shown specifically for the infective third stage larvae (iL3s) of S. venezuelensis (Islam et al . 1999). …”