Cross-immunity in rats infected with different Trichinella species
Britov, V.A.
Wiadomosci Parazytologiczne 21(4-5): 633-638
1975
ISSN/ISBN: 0043-5163 PMID: 1189436 Document Number: 94852
White rats were immunized with 400 to 600 60-day-old Trichinella spiralis larvae (from rats) and were challenged 50 days later with either 7,000 or 14,000 T. pseudospiralis larvae. 2 rats from the latter group died within 2 days; the condition of the remaining rats had improved by day 7 after challenge, while all controls (receiving the challenge doses only) died in 3 to 34 days. Autopsy on day 35 showed that rats with heavy initial infections (542 to 1,406 larvae/200 mg macerated muscle) were fully protected but those with low to medium infections (14 to 498 larvae/200 mg) were only partially protected. In the 2nd test, rats infected with 200 to 2,000 T. nelsoni larvae (achieving infections of 2 to 931 larvae/200 mg) were challenged with 2,000 T. spiralis larvae. All animals became infected but the intensity of infection was a fifth of that in controls (receiving the second infection only). However in this test, the take of the challenge dose was not related to the strength of the immunizing infection. In the 3rd test, immunization was with 400 to 600 T. pseudospiralis larvae and challenge with 2,000 or 6,000 T. spiralis larvae. All controls and several experimental rats receiving the higher challenge dose died. All remaining rats showed symptoms of severe infection and were killed 45 days after challenge. The average take of the challenge dose was about a quarter of that in controls, indicating the presence of a relatively week immunity in comparison to the first test.