Multielement assays of bovine tissue specimens by inductively coupled argon plasma emission spectroscopy

Inductively coupled argon plasma spectroscopy was used to generate multielement profiles of bovine serum (n = 607), liver (n = 229), and kidney (n = 90) samples submitted to the Animal Health Diagnostic Laboratory at Michigan State University, East Lansing. The presented frequency distribution histograms of element concentrations in the different samples provided a data base for diagnostic interpretations and illustrated some of the advantages, as well as limitations, of inductively coupled argon plasma for this purpose.     

Bovine leukemia virus: A herd-based control strategy

A study was conducted in order to develop a herd-based control strategy for bovine leukemia virus (BLV). Michigan State University's closed lactating dairy herd of 114 cows was utilized for the study. Ninety-five percent (95%) of the cows were positive for BLV antibodies, as determined by the agar gel immunodiffusion (AGID) test in November 1979. To develop the control strategy program, the following management practices were instituted: there was a complete physical separation of BLV positive from BLV negative animals for 3 years after which the two groups were physically mixed. Different and sterile supplies and equipment were utilized for any veterinary-medicine-related activity. Personnel working on the farm were constantly made aware of the transmission of the disease and how to minimize it. A constant vector control program and other miscellaneous management practices were implemented. The BLV seronegative animals were examined monthly for BLV antibodies starting at 6–7 months of age. The reactor animals were separated from the seronegative animals when the reactors had 2 positive AGID tests consecutively. A positive BLV serotest was not a criterion for culling. Following a 3-year complete separation of positive animals from negative animals, the overall point prevalence decreased from 95 to 34%. The results were further categorized according to 4 age groups of 6–15, 16–23, 24–47 and 48 months and older. The percentage of BLV-positive animals decreased from 19 to 17, 58 to 14, 90 to 33 and 100 to 90% for the respective age groups. Following a 10-month discontinuation of physical separation of positive animals from negative animals, a decrease in the overall point prevalence rate was still observed. The limitations and practical applications of the program are discussed.     

In vitro stimulation of bovine peripheral blood lymphocytes: effect of short-term storage of blood prior to lymphocyte culture

Storage of peripheral blood from Mycobacterium bovis-sensitized cattle from 1 to 48 hours at 4, 22, and 37 C was shown not to alter markedly the lymphocyte blastogenic response to M bovis-purified protein derivative. Concanavalin A-induced lymphocyte mitogenic responses were unaffected by storage of blood for 1, 24, or 48 hours at 22 C and 37 C; however, storage of blood for 48 hours at 4 C significantly lowered (P less than 0.05) mitogenic responses to concanavalin A, as compared with responses to blood kept at 22 C. Mononuclear cell recovery from stored blood at all temperatures was markedly less than that from freshly drawn blood samples. Cell recoveries were most affected by storage of blood at 4 C and 37 C.     

Effect of surfactants on weight gain in mice

A study was conducted to determine if four surfactants can induce increased weight gain in the mouse. Basic-H, Triton X-100, Amway All Purpose Adjuvant and X-77 were put in water and fed to various groups of ICR 21 day old female mice for a period of 43 days. All the mice were clinically normal throughout the study period. Pathological examination of a random sample of the mice revealed no gross pathological changes. Similarly, histopathological examination of the lungs, livers and intestines did not reveal any visible lesions. Basic-H and Amway surfactants induced weight gain, though not significantly, better at 0.1% (V/V) concentration while X-77 and Triton X-100 induced weight gain better at 0.4% (V/V) concentration. Overall results show that none of the surfactants tested induced significant weight gain.     

Comparison of Sarcocystis neurona isolates derived from horse neural tissue

Sarcocystis neurona is a protozoan parasite that can cause neurological deficits in infected horses. The route of transmission is by fecal-oral transfer of sporocysts from opossums. However, the species identity and the lifecycle are not completely known. In this study, Sarcocystis merozoites from eight isolates obtained from Michigan horses were compared to S. neurona from a California horse (UCD1), Sarcocystis from a grackle (Cornell), and five Sarcocystis isolates from feral opossums from Michigan.Comparisons were made using several techniques. SDS-PAGE analysis with silver staining showed that Sarcocystis spp. from the eight horses appeared the same, but different from the grackle isolate. One Michigan horse isolate (MIH6) had two bands at 72 and 25kDa that were more prominent than the UCD1 isolate and other Michigan horse isolates. Western blot analysis showed that merozoites of eight of eight equine-derived isolates, and the UCD1 S. neurona isolate had similar bands when developed with serum or CSF of an infected horse. Major bands were seen at 60, 44, 30, and 16kDa. In the grackle (Cornell) isolate, bands were seen at 60, 44, 29, and 16kDa. DNA from merozoites of each of the eight equine-derived isolates and the grackle-derived isolate produced a 334bp PCR product (Tanhauser et al., 1999). Restriction fragment length polymorphism (RFLP) analysis of these horse isolates showed banding patterns characteristic for S. neurona. The grackle (Cornell) isolate had an RFLP banding pattern characteristic of other S. falcatula species. Finally, electron microscopy examining multiple merozoites of each of these eight horse isolates showed similar morphology, which differed from the grackle (Cornell) isolate. We conclude that the eight Michigan horse isolates are S. neurona species and the grackle isolate is an S. falcatula species.     

Application of a whole-blood lymphocyte stimulation test in detection of Brucella infection in an outbreak

A whole-blood lymphocyte stimulation test (WBLST), the standard plate and tube agglutination tests, the Brucella buffered antigen test, the 2-mercaptoethanol agglutination test, the Rivanol plate precipitation test and bacteriological isolation were utilized in a brucellosis outbreak investigation in a beef herd. Three of the animals were classified as not infected serologically. However, these 3 animals were classified as infected on the WBLST, andBrucella abortus biotype 1 (not strain 19) was isolated from their lymph nodes. The WBLST exhibited significant sensitivity in this investigation and more observations of this nature might strengthen the application of this assay in similar situations.     

Temporal cell-mediated immune responses of cattle following experimental and natural exposure to living Brucella abortus.

A study on cell-mediated immune responses in cattle with different exposure experiences to Brucella abortus was conducted by an in vitro lymphocyte stimulation assay. The purpose of this study was to determine how soon the cell-mediated immune responses would be detected following experimental exposure to B. abortus and to study the cell-mediated immune trend following experimental and natural exposure of cattle to B. abortus. The first positive cell-mediated immune responses occurred one to two weeks after experimental inoculation with living B. abortus strain 2308. The cell-mediated immune responses in these animals appeared at least one week before the appearance of of B. abortus serum agglutinating antibodies. Animals which were naturally infected with B. abortus biotypes 1 and 2 demonstrated positive cell-mediated immune responses throughout the study.     

Epidemiologic investigation of Mycobacterium bovis in a population of cats

OBJECTIVE: To determine whether cats exposed at a residence were infected with Mycobacterium bovis, whether the tuberculin skin test can identify cats infected with M bovis, and whether an ELISA could identify tuberculosis-infected cats. ANIMALS: 20 domestic cats exposed to a cat with laboratory-confirmed disseminated M bovis infection. PROCEDURE: Cats were administered a tuberculin skin test and monitored for 72 hours. Blood and fecal samples were collected. Cats were then euthanatized, and postmortem examinations were performed. Tissues were examined grossly and histologically for signs of mycobacteriosis. Pooled tissue samples and fecal samples were submitted for mycobacterial culture. Blood samples were examined for evidence of tuberculosis by use of a comparative ELISA. RESULTS: 4 cats had positive responses for the ELISA, and 2 cats had suspicious responses. All tuberculin skin tests yielded negative results. No gross or histologic lesions of tuberculosis were detected in any tissues, and mycobacteria were not isolated from tissues or feces obtained from the 20 cats. CONCLUSIONS AND CLINICAL RELEVANCE: All cats that had positive or suspicious responses for the ELISA were offspring of the cat with tuberculosis. Evidence of tuberculosis was not seen in other cats at the residence, the owner, or the attending veterinarian. The most likely source of tuberculosis for the infected cat was through the consumption of M bovis-infected wildlife carcasses or offal. Because M bovis is endemic in wildlife in northeastern Michigan, there is a risk of exposure to tuberculosis in companion animals, their owners, and attending veterinarians.     

Levamisole potentiation of antigen specific lymphocyte blastogenic response in Brucella abortus exposed but nonresponsive cattle

Incubation of Brucella abortus (field strain) infected and strain 19 vaccinated bovine peripheral blood lymphocytes with B. abortus antigen and levamisole caused a consistently significant increase in [3H] thymidine uptake when compared to cultures without levamisole. Levamisole did not potentiate B. abortus-induced blastogenic response of lymphocytes from non-exposed cattle. A dose response study showed that 10 micrograms/culture induced maximum potentiation of B. abortus-induced lymphocyte stimulation. Using the 10 micrograms/well concentration of levamisole, further studies were conducted to determine the net potentiation of the blastogenic responses in lymphocytes from B. abortus (field strain) infected cattle. B. abortus strain 19 vaccinated but nonresponsive and non-exposed cattle. Levamisole significantly potentiated the B. abortus-induced lymphocyte blastogenesis in lymphocytes from unresponsive cattle.