Oral vaccination against coccidiosis: responses in strains of mice that differ in susceptibility to infection with Eimeria vermiformis

Abstract

Four strains of mice with different susceptibilities to Eimeria vermiformis were orally dosed with a crude antigen prepared from sporulated oocysts of the parasite, with or without cholera toxin as adjuvant. The effect on subsequent challenge infections depended on the resistance and susceptibility phenotypes of the host: oocyst production was reduced in susceptible C57BL/6 and NIH mice but increased in resistant BALB/c and C3H mice. Despite this contrast, no fundamental differences were detected between the immune responses of BALB/c and C57BL/6 mice, either to vaccination or after superimposed infection, but the suppressing and enhancing effects of vaccination were transmissible to naive recipients via suspensions of mesenteric lymph node cells. The results obtained are compared with those previously reported for parenterally immunized BALB/c and C57BL/6 mice.

Vaccination against coccidiosis: host strain‐dependent evocation of protective and suppressive subsets of murine lymphocytes

“…protection of C57BL/6 mice; increased infections in BALB/c mice), but differing ones on cellular proliferation postinfection (p.i.). Thus, in both strains, proliferation was suppressed after parenteral vaccination (Rose et al 1996b) but enhanced after oral vaccination (Rose et al 1997).…”

“…Mice were immunized either orally (Rose et al 1997) or parenterally (Rose et al 1994(Rose et al , 1996b, the regimen in each case consisting of two or, more usually, three doses of antigen in a volume of 200 ml.…”

“…Previous measurements of the effects of vaccination on speci®c IgG serum antibody responses by the two strains have indicated that, whereas BALB/c mice produce higher levels of antibodies after parenteral vaccination, B6 mice are more reactive after oral immunization (Rose et al 1996b(Rose et al , 1997. Here, in an attempt to characterize further the cells involved in the depressive or protective effects of vaccination, the serum samples obtained in the above oral vaccination experiments were examined for the isotype (IgG1 or IgG2a) of the antibodies that bound to E. vermiformis-antigen.…”

“…We have used the E. vermiformis system to examine the effects of immunization with crude parasite antigens on subsequent challenge infections and found that the results depended upon the susceptibility phenotype of the host to infection: normally more resistant strains of mouse (BALB/c, C3H) were rendered susceptible, whereas less resistant strains (C57BL/6, NIH) were protected by this procedure (Rose et al 1994(Rose et al , 1996b(Rose et al , 1997. This effect was antigen-speci®c since infection with another Eimeria spp.…”

“…was unaffected, as were immune responses to unrelated antigens (Rose et al 1996b). The changes in susceptibility phenotype induced by vaccination were not re¯ected in appreciable differences between the strains in the levels of antibodies produced in response to immunization, nor in the proliferative responses of their mesenteric lymph node cells (MLNC), or splenocytes, to stimulation with speci®c antigen ex vivo, but they were transmissible to naive recipients via suspensions of MLNC (Rose et al 1996b(Rose et al , 1997. A puzzling feature was that vaccination by either the parenteral or the oral route produced similar effects on hostsusceptibility (i.e.…”