Immunomodulation of lambs following treatment with a proteasome preparation from infective larvae of Trichostrongylus colubriformis

Abstract

Proteinases are known to be capable of prolonging the survival of endoparasites in a host. We were therefore interested in knowing whether immunization of lambs against a proteasome (multisubunit proteinases) preparation obtained from Trichostrongylus colubriformis infective third-stage larvae (L3) would have any effect on the immune response to a single challenge infection with the same organism. A total of 21 penned lambs aged 8 months were divided into 3 equal groups. Group 1 was immunized on three occasions with increasing amounts of a proteasome-enriched fraction obtained from infective L3. Group 2 was given a similar amount of protein from the initial supernatant of homogenized larvae. Group 3 (controls) received adjuvant plus saline solution only. All groups were challenged with 60,000 infective T. colubriformis larvae at 28 days after the last immunization. Significant protection was obtained only when the initial supernatant extract was used to immunize lambs. The proteasome preparation seemed to have immunosuppressive effects through the stimulation of nonspecific IgE production. Significantly lower levels of specific IgE were observed in lambs immunized with the proteasome-enriched fraction, and levels of specific IgG antibodies were increased. We suggest that proteasome fractions of T. colubriformis may serve as useful preparations for the study of mechanisms of IgE production in parasitized sheep.

IgG responses to salivary gland extract of Ixodes ricinus ticks vary inversely with resistance in naturally exposed sheep

“…The relationship between total IgG concentrations and IgG isotypes in type 1 and type 2 responses in sheep is largely unexplored and reagents that could discriminate between different IgG isotypes in sheep are not currently available. There is, however, evidence that in sheep, type 2 responses to macroparasite antigens are associated with raised total IgG concentrations (Moskwa, 1999; Stankiewicz & Hadas, 2000; Stankiewicz et al ., 2000).…”

Predicting the effects of parasite co-infection across species boundaries

“…While there is evidence that Trichostrongylus spp. may have some immunomodulatory capacity, it does not appear to be as immunologically broad ranging as that observed among the blood-feeding species [ 16 , 32 ]. Further evidence of the different immune responses to these parasite groups is seen in rabbits, where the temporal pattern of natural and laboratory infections suggests that T. retortaeformis is effectively removed by the host, while G. strigosum is not [ 3 , 33 ].…”