Vaccination of Chinese bovines (cattle and buffaloes) against schistosomiasis japonica with 36 kR gamma-irradiated schistosomula was done for laboratory challenge and for field trials in China. Altogether, 61 bovines were used. All experimental animals were vaccinated 2-3 times with 10,000 irradiated schistosomula per time. For the laboratory challenge, all experimental and control cattle were challenged with 500 normal cercariae and each buffalo, with 2,000 cercariae. The laboratory-challenged bovines were killed after 54-57 days of challenge; the bovines for the field trial in the lightly endemic area, after 5 months in the field; and the bovines for the field trial in the heavily endemic area, after 58-63 days. When the animals were killed, the number of mature worms in the vaccinated (experimental) and non-vaccinated (control) animals was recorded and the percentage of worm reduction in each group was calculated. The first group, consisting of three vaccinated and three non-vaccinated cattle, was given a laboratory challenge; the worm reduction was 71.6%. The second group, consisting of two vaccinated and three non-vaccinated buffaloes, was also given a laboratory challenge; the worm reduction was 74.4%. The third group, consisting of seven vaccinated and eight non-vaccinated buffaloes, was utilized in a field trial in a lightly endemic area; the worm reduction was 75.6%. The fourth group, consisting of eight vaccinated and nine non-vaccinated cattle, and the fifth group, consisting of nine vaccinated and nine non-vaccinated buffaloes, were pastured in a heavily endemic area. The worm reduction was 65.1% in the fourth group and 75.7% in the fifth group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1983

Histopathological study of the attrition of challenge cercariae of Schistosoma mansoni in the skin of mice immunized by chronic infection and by use of highly X-irradiated cercariae.

To find direct evidence for the sites of death of newly transformed schistosomula of Schistosoma mansoni in the skin of challenged immunized hosts, a histopathological study of the skin of chronically infected mice and of highly X-irradiated cercaria-immunized mice was made at different post-challenge times. Attrition of infecting organisms in naive mice was used as a control. In general, three main kinds of schistosomular attrition were observed: (1) in the granulocytic exudates in the epidermis, (2) in the granulocytic aggregates in the subcutaneous tissue, and (3) in the granuloma-like foci in the subcutaneous tissue. Schistosomula killed by the epidermal granulocytic exudates and by the subcutaneous granuloma-like foci occurred in all three groups of mice, but the schistosomula killed by the subcutaneous granulocytic aggregates were found only in the highly X-irradiated cercaria-immunized animals. Schistosomula killed by the epidermal granulocytic exudates were encountered occasionally in the challenged naive mice but more frequently in both the challenged chronically infected mice and the challenged highly X-irradiated cercaria-immunized mice. The number of subcutaneous granuloma-like foci was greater in the challenged mice immunized with highly X-irradiated cercariae than in the challenged naive mice or the challenged chronically infected mice. Another differentiating character among the three groups of mice was that in the highly X-irradiated cercaria-immunized group, the subcutaneous granuloma-like foci appeared on day 3 after the challenge, but on day 5 in the naive and chronically infected groups. The results clearly indicate that skin is an important site for the attrition of the challenged cercariae in the highly X-irradiated cercaria-immunized mice, and that immunity in the chronically infected and X-irradiated cercaria-immunized mice occurs by different mechanisms.

Animals↗

PubMed1983

Vaccination against bovine schistosomiasis japonica with highly X-irradiated schistosomula.

Cercariae of the Chinese mainland strain of Schistosoma japonicum were used. Eighteen cattle, divided into six groups of three each, were immunized with schistosomula transformed from cercariae exposed to three different doses of X-irradiation (24, 36, and 48 kR). The immunization was given either once, twice, or thrice, and the number of immunizing schistosomula was 10,000 or more in each immunization. The immunized cattle were challenged with 500 normal cercariae. Five native cattle were similarly infected with normal cercariae as controls. All cattle were killed 32-33 days after challenge or infection, and the worms were obtained by perfusion. The mean worm reduction in the 18 experimental animals varied from 42.1 to 96.0%. The mean percent worm reduction of the six experimental groups varied from 54.8 to 87.1. The reduction was greater with increasing numbers of immunizations, and was higher in the groups immunized with schistosomula exposed to 36 kR than in those exposed to 24 or 48 kR. Statistical analyses showed that all immunized groups yielded significantly fewer worms than controls. However, the three doses of X-irradiation (24, 36, and 48 kR) had no significant effect for a fixed number of immunizations (1, 2, or 3). The means for both two and three immunizations were significantly different from the mean for one immunization, although they were not significantly different from each other.

Animals↗

PubMed1983

Immunization of mice with ultraviolet-irradiated Schistosoma mansoni cercariae: a re-evaluation.

Mice immunized by percutaneous exposure to ultraviolet-irradiated Schistosoma mansoni cercariae developed levels of resistance to subsequent S. mansoni infection comparable to those induced by gamma-irradiated cercariae (50-70% reduction in adult worm burden). Cercariae treated with ultraviolet doses ranging from one to three times the minimum dose required to prevent long-term survival induced the highest levels of resistance.

Animals↗

PubMed1982

[Degenerative thoracic spinal stenosis].

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