Protection from parasite-induced weight loss by the vaccination of calves with excretory-secretory products of larval Oesophagostomum radiatum.

Excretory-secretory products (ESP) were collected from in vitro maintained Oesophagostomum radiatum larvae during the period in which the larvae molt from the third to fourth larval stage. The ESP were used to immunize 13 uninfected calves which were subsequently challenged with 1.7 X 10(4) infective O.

Screen for anthelmintics, using larvae of Ascaris suum.

A multiwell culture system was used to assay the effects of 12 known anthelmintic compounds on Ascaris suum larval development from 2nd-stage (L2; hatched from eggs) to early 3rd-stage (L3) and from in vivo-derived late L3 to early 4th-stage (L4). Larval survival, development, and motility were monitored for drug effects. Development of L2 to L3 was sensitive to thiabendazole, albendazole (ABZ), ABZ/sulfoxide, ABZ/sulfone (SO), mebendazole, L-tetramisole, D-tetramisole, piperazine, or closantel at a concentration of 0.

Suppression of antigen- and mitogen-induced proliferation of bovine lymphocytes by excretory-secretory products of Oesophagostomum radiatum.

Excretory-secretory products (ESP) isolated from in vitro-grown stage-3 to -4 larvae of Oesophagostomum radiatum were found to inhibit both the in vitro antigen-specific proliferation of keyhole limpet hemocyanin- and ovalbumin-primed lymphocytes and the proliferation induced by the T-cell mitogen concanavalin A. As little as 50 ng of ESP protein per culture resulted in 50% reductions of subsequent proliferative responses. Antigen-induced responses were 100 to 1,000 times more sensitive to inhibition than were mitogen-induced responses.

Infectivity and pathogenicity of three isolates of Ostertagia ostertagi in cattle.

Two laboratory-maintained isolates of Ostertagia ostertagi and 1 recently isolated from grazing cattle, were compared for their infectivity and pathogenicity in Holstein-Friesian calves. Calves were inoculated with 200 000 and 300 000 infective larvae in 2 experiments. Calves in both experiments developed anorexia and diarrhea; generally calves were more severely affected by the larger inoculum.

Culture requirements of Ascaris suum larvae using a stationary multi-well system: increased survival, development and growth with cholesterol.

Ascaris suum third-stage larvae (L3) were recovered from infected rabbits and cultured in a stationary multi-well plate system. Several different culture media including Medium 199, NCTC-135, Minimum Essential Medium-Eagle, Dulbecco's Modified Eagle's Medium, RPMI 1640, McCoy's 5A and Neuman-Tytell medium were tested to determine which was best for overall larval survival, development and growth. Larvae developed from L3 to fourth-stage (L4) in all media tested, but larval survival and the yield and growth of L4 were superior in RPMI 1640.