Schistosoma mansoni: challenge attrition during the lung phase of migration in vaccinated and serum-protected rats.
Serum harvested from Sprague-Dawley rats twice vaccinated with gamma-irradiated cercariae of Schistosoma mansoni is able to protect naive recipients against a challenge infection, but the challenge parasites are susceptible to immune elimination over a very short period of time. Thus, vaccinated rat serum protects recipients against a percutaneous cercarial challenge when transferred on Day +5 but not Day 0 and protects recipients against a tail vein challenge with 5-day-old lung worms when transferred on Days 0 or +1, but not Days +4 or +5. Rats challenged with lung worms via the tail vein and given serum on Day +3 exhibit approximately half the protection expressed by counterparts that received serum on Day 0. However, vaccinated rat serum does not protect naive recipients against a lung worm challenge introduced directly into the liver. These data indicate that immune elimination of challenge parasites in the vaccinated rat model is site-dependent rather than stage-dependent, and most probably occurs during the lung phase of parasite migration.
D000818:Animals; D005260:Female; D007116:Immunization, Passive; D007275:Injections, Intravenous; D007814:Larva / Q000276:immunology; D008099:Liver / Q000469:parasitology; D008168:Lung / Q000469:parasitology*; D008642:Mesenteric Veins; D051379:Mice; D008808:Mice, Inbred CBA; D051381:Rats; D011919:Rats, Inbred Strains; D012550:Schistosoma mansoni / Q000276:immunology; D012552:Schistosomiasis / Q000276:immunology* / Q000469:parasitology; D013623:Tail / Q000098:blood supply; D013997:Time Factors; D014611:Vaccination