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  • Author or Editor: B. L. Blagburn x
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Abstract

Objective

To determine whether an estradiol-progesterone (EP) growth implant would have an effect on febrile responses and on the catabolic component of Eimeria bovis infection.

Animals

27 Holstein bull calves.

Procedure

Calves were assigned to treatment groups as: control (n = 5), EP implant (EP, n = 5), E bovis-inoculated (coccidia: C, n = 7), pair fed (n = 4), or EP plus E bovis-inoculated coccidia (EP/C, n = 6) groups. Calves were provided subcutaneous EP implants at 8 weeks of age, and were inoculated with 2 × 105 oocysts of E bovis at 11 weeks of age. Body weight was measured on postinoculation day (PID) 0, 14, and 28. Rectal temperature and food intake were determined and fecal samples were collected daily from PID 15 to 28. Blood samples were collected on PID 24 for analysis of CD2+, CD4+, and CD8+ antigens and plasma insulin-like growth factor I concentration. Blood samples were collected at 15-minute intervals for measurement of pulsatile growth hormone release.

Results

Group-EP/C calves had fever for 2 days versus 5 days for group-C calves (P < 0.05). These calves had diarrhea for fewer days than did their group-C counterparts (P < 0.05). Fibrinogen and glucose values were high in group-C (P < 0.05) but not group-EP/C calves. The latter had positive weight gain from PID 14 to 28, whereas group-C calves had weight loss (P < 0.05). Plasma insulin-like growth factor I concentration was reduced by infection (P < 0.05). EP-treated noninfected calves had increased numbers of CD2+, CD4+, and CD8+ blood mononuclear cells (P < 0.05).

Conclusions

EP has a protective effect in calves infected with E bovis. This may relate to changes in immune function induced by EP.

Clinical Relevance

Treatment of calves with EP could offer some protection against the often severe wasting and debilitation associated with E bovis infection. (Am J Vet Res 1997;58:891–896)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To examine cross-reactivity among Neospora caninum and closely-related apicomplexans.

Design

Sera from animals were examined for antibody production to N caninum and cross-reactivity to Toxoplasma gondii.

Animals

Cattle were experimentally infected with 3 tissue cyst-forming protozoan parasites N caninum, T gondii, and Sarcocystis sp, and calves were monospecifically inoculated with the intestinal coccidia, Eimeria bovis and Cryptosporidium parvum. Similar studies were done in laboratory rabbits inoculated with N caninum, T gondii, Hammondia hammondi, and Sarcocystis sp. Additionally, sera were obtained from ewes, lambs, goats, sows, cats, rats, and mice inoculated with N caninum tachyzoites.

Procedure

The indirect fluorescent antibody (IFA) and ELISA antibody tests (cattle only) were used to examine reactivity to N caninum; the modified direct agglutination, Sabin-Feldman dye, and IFA tests were used to evaluate reactivity to T gondii.

Results

Serologic cross-reactivity among N caninum, T gondii, and Sarcocystis sp was none or minimal by the IFA test. There was some reactivity to N caninum by the use of ELISA in cattle inoculated with Sarcocystis sp.

Conclusions

The IFA test for N caninum was specific for the diagnosis of neosporosis in animals.(Am J Vet Res 1996;57:329-336)

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

SUMMARY

Neospora caninum-induced abortion is a major production problem in the dairy cattle industry in the United States and worldwide. Abortions attributable to naturally acquired N caninum infection also have been observed in pygmy goats. We studied experimentally induced infections with N caninum in pregnant pygmy does to determine whether abortions attributable to N caninum infection would occur after inoculation. Seven pregnant pygmy does (1 control doe and 6 inoculated with N caninum) were studied. The control doe remained clinically normal throughout the study and delivered 2 healthy kids. Abortion, fetal death, and stillbirths were observed in some pregnant does inoculated with N caninum. Two pregnant pygmy does inoculated with N caninum early in gestation (day 51) had fetuses that died and were aborted, or died and were reabsorbed. Neospora caninum tachyzoites and lesions were observed in the brain, spinal cord, and heart of aborted fetuses; parasites also were isolated from the placenta. Four additional pregnant pygmy does (2 inoculated at mid-gestation [day 85], and 2 at late gestation [day 127]) did not abort after inoculation. However, 1 doe inoculated during midgestation delivered a stillborn fetus that had died about 1 week prior to parturition. This kid was congenitally infected with N caninum. Neospora caninum was isolated from the placentas of all inoculated does examined. Neonatal neosporosis was not observed in live-born kids, nor were stages of N caninum isolated from any live-born kid. Does did not undergo abortion or have congenitally infected kids when they were rebred and evaluated for neosporosis.

Free access
in American Journal of Veterinary Research

Summary

Ultrastructure of the interactions of host cell mitochondria with developing Toxoplasma gondii tissue cysts was examined in cultured cells, using transmission electron microscopy of infected cells and rhodamine 123 (a mitochondria-specific vital fluorescent dye) staining of isolated tissue cysts. Structurally mature T gondii tissue cysts were observed as early as 2 days after inoculation of cultured cells. During development of T gondii, host cell mitochondria were observed surrounding the parasitophorous vacuole membrane. Mitochondria became flat and elongated in the vicinity of the parasitophorous vacuole membrane. These mitochondria were also closely associated with T gondii tissue cysts. Incubation of tissue cysts from cultured cells and tissue cysts from mouse brains with rhodamine 123 revealed fluorescence of the tissue cyst wall in living specimens. Incubation of tissue cysts with 10 µM rotenone caused diminished fluorescence of the tissue cyst walls, and 100 µM rotenone caused complete inhibition. Mouse RBC, and tissue cysts fixed in 100% methanol did not fluoresce after exposure to rhodamine. Tissue cysts in 9 isolates of T gondii from mouse brains were examined, using rhodamine 123, and the tissue cyst walls of all isolates fluoresced, indicating no isolate effects. Our results indicate that host cell mitochondria may be closely associated with the tissue cysts of T gondii in cell cultures and in mice.

Free access
in American Journal of Veterinary Research

SUMMARY

The ultrastructure of tachyzoites of 3 isolates of Neospora caninum from dogs was examined, using transmission electron microscopy of infected cultured cells. Ultrastructure of the 3 isolates was similar. Tachyzoites had a pellicle, 22 subpellicular microtubules, a conoid, anterior and posterior polar rings, 8 to 12 electron-dense rhoptries, numerous micronemes, a single vesicular nucleus, tubular mitochondria, Golgi complexes, ribosomes, endoplasmic reticula, an inactive micropore, electron-dense bodies, lipid bodies, and amylopectin bodies. Most tachyzoites were located adjacent to the host cell nucleus in a parasitophorous vacuole that contained numerous intravacuolar tubules. Tachyzoites divided by endodyogeny. Neospora caninum tissue cysts were not seen. Comparison of N caninum with Toxoplasma gondii tachyzoites indicated that the 2 species can be differentiated on the basis of structure and numbers of rhoptries and numbers and location of micronemes and electron-dense bodies.

Free access
in American Journal of Veterinary Research