The In-vitro Development of Cooperia pectinata, a Nematode Parasite of Cattle, from Third-Stage Larvae to Adults, including Egg Production

Abstract

Cooperia pectinata was cultivated in vitro from artificially exsheathed third-stage larvae to egg-laying (unfertilized) or sperm-containing adults. The intervals required for development of fourthand fifth-stage larvae in vitro did not differ greatly from those in vivo whereas the production of eggs took slightly more than twice as long in vitro. Populations produced in vitro contained a smaller percentage of adults than those produced in vivo. Fourth-stage larvae accumulated in vitro. Adults produced in vitro were smaller than adults in vivo. C. pectinata and C. punctata exhibited comparable development in an in-vitro system. In an in vitro system utilizing a fluid medium composed of chick embryo extract, serum, sodium caseinate, vitamins, a hog-liver extract, a balanced salt solution, an indicator, antibiotics, and gassed with CO2 to pH 7.2 to 7.3, it was possible in tubes placed in a roller drum to obtain the development of one or more of the parasitic stages of some nematode species of cattle, sheep, and swine (Leland, 1961, 1963, 1965b). In this system, four of the species, Cooperia punctata, Ostertagia ostertagi, 0. circumcincta, and Hyostrongylus rubidus developed to egg-laying adults (Leland, 1963, 1965b). The present report describes the type of development that occurred when Cooperia pectinata, an intestinal nematode of cattle, was cultured in the previously described system using medium Ae (Leland, 1963) and in two modifications of this medium, namely, AL and Ap. Portions of this work have been previously reported in abstract (Leland, 1965a). MATERIALS AND METHODS Infective larvae of C. pectinata, cultured from manure collected from calves harboring a monospecific infection of this nematode, were obtained from Dr. H. Herlich of the Regional Animal Disease Research Laboratory, USDA, Auburn, Alabama. A portion of these larvae was processed as described below and used directly in the culture system (H-Inoculum, Table I). The remaining portion was used to infect a helminth-free calf, which thereafter served as a source of C. pectinata