Search

Ovine progressive pneumonia is caused by a lentivirus of known infectivity only for sheep and goats. Virus susceptibility of 11 other species of animals was examined. Species included cattle, chickens, deer, dogs, goats, hamsters, horses, mice, pigs, rabbits, and rats. Of these species, only goats and rabbits could be experimentally infected with the virus. The infection in rabbits was acute, and virus did not persist or induce antibody production as it does in sheep and goats. Sera obtained from several people working in close contact with the virus and from several wild species, with unknown exposure history, were tested for antibodies to viral antigens. All results were negative. Knowledge of the host range of this virus is important for scientific studies and for virus eradication programs.

The results from studies to measure lytic complement (C') in sera of different animal species were reviewed. The traditional system, using sheep red blood cells (RBC) and rabbit antibody, was confirmed as the most sensitive to measure C' levels in man, monkey, dog, guinea pig, and rat serums. Sera C' from horse, cow, and sheep were found to be best assayed using rabbit RBC, whereas C' from goat, cat, and rabbit were best assayed with human RBC. Antibodies and C' from the same species usually mediated lysis of foreign RBC, but this lysis occurred more readily with some RBC targets than with others and may be associated with the presence of natural antibodies in the test sera. The effects of the species origin of a C' source in immunologic reactions in vitro and in vivo are discussed.

The prevention of hamster-associated outbreaks of lymphocytic choriomeningitis virus infection in human beings requires rapid and reliable testing of large numbers of hamsters for the infection. To select the most effective test, the antibody response of infected hamsters was determined by the indirect fluorescent antibody and complement-fixation techniques. The indirect fluorescent antibody technique required less than 2 hours to complete, was the first to become positive after infection, and remained positive for at least several months. Infection in hamsters was also readily detected by the inoculation of mice with infected hamster tissues; virus could be isolated from several organs as early as postinoculation day (PID) 3, and all organs tested contained high concentrations of virus by PID 5. After PID 40, virus was detectable only in the kidney; this organ remained positive for over 3 months.

Using a 51Cr-release microcytotoxicity assay, natural cytotoxic cell activity was demonstrated in the peripheral blood of clinically normal, nonimmune cats. Cytotoxicity was enhanced against virus-infected feline cells over that in noninfected cells. Xenogeneic mouse and hamster target cells were also susceptible to lysis. The cytotoxic activity increased as effector-to-target cell ratios were increased and required a 16-hour assay to be expressed. The specificity of the natural cytotoxicity was selective in that some, but not all, target cells tested were susceptible to lysis. Characterization of the cytotoxic cells showed them to be nonadherent and to possess Fc receptors for immunoglobulin G.

Wild and domestic animals from 3 geographic-climatologic areas in northern California were tested for antibodies against Toxoplasma gondii. A total of 2,796 serum samples representing 37 species of wild mammals, 35 species of wild birds, and 5 species of domestic animals were tested by the indirect hemagglutination test. Of 1,174 wild mammal serums tested, 10.8% were positive, which compared with 14.7% of the 1,221 domestic mammal serums. Of 229 wild carnivores tested, 45% were seropositive, including 69% of 86 bobcats, 28% of 58 coyotes, 48% of 25 raccoons, 27% of 26 gray foxes, 22% of 32 striped skunks, a civet cat, and a mink. Serologic evidence of infection was found in 38% of 47 rural domestic cats, but none of the 7 dogs tested was seropositive. Of 160 murid rodents (rats and house mice) in rural habitats, 4% were seropositive, which compared with 2% of 399 cricetine rodents (mostly deer mice) collected from wilderness habitats. Seven percent of 56 wild Artiodactyla (deer and feral pigs) were seropositive, which compared with 15% of 1,048 domestic sheep tested. Of 401 birds tested, 3.5% had antibodies against T gondii. The highest prevalence of antibodies among birds was in crows (14%). Toxoplasma was isolated from 1 raven, by mouse inoculation. In general, the highest prevalence of seropositive carnivores, rodents, and sheep was in the coastal region below 100 ft elevation, where the weather is cool and damp for much of the year. In the central valley the highest prevalence among sheep was in areas under irrigation. The prevalence of antibodies was lowest in the mountain areas, where climatologic extremes prevail at various seasons of the year.

Serum samples (n = 1,146) representing 100 species of exotic ruminants now captive in United States zoos were assayed for neutralizing antibody to infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus 1). Thirty-four animals (3%) of 11 species had antibody to IBR virus. Because of the low prevalence of IBR antibody found, it was concluded that vaccination against IBR virus probably is not necessary for captive wild ruminants in United States zoos.

Total complement (C) and its components were assayed in the serum of 8 species of domestic animals, using commercially prepared cellular intermediates of sheep erythrocytes and functionally pure guinea pig and human components of the C system. Testing was done according to methods recommended by the producer for testing human C components. The late-acting components (C6 throug C9) and C1 were detected in carnivorous (dog and cat) and omnivorous (swine) animals. Undetectable or low titers of C4, C2, C3, and C5 were present in large herbivorous animals (cattle, horse, sheep, and goat), indicating major differences in comparison with human or guinea pig components of C. Porcine serum contained an inhibiting substance which interfered with testing C2 and later-acting components at serum dilutions up to 1:100. All components except C2 were detected in chicken serum. The binding or activation (or both) of C4, C2, C3, and C5 is more species specific than is the binding or activation (or both) of other components. Requirements for species specificity between antibody and C1 were not detected. Presence of C1 inactivator was detected in bovine, caprine, equine, and ovine sera. The CH50 (50% hemolysis) titers of C components tested in pooled serum samples from the 8 species of clinically healthy domestic animals are presented.

An epidemiologic study was done on a ranch in northern California on a flock of ewes that had a history of abortions, mummified fetuses, weak or stillborn lambs, and failure to conceive. Of 56 ewes tested, 33 (59%) had serum agglutinating antibodies against Toxoplasma gondii, with an unusually high proportion of high titers. Over a 2-year-period, reproductive problems were higher (39% to 42%) among the seropositive ewes than among the seronegative ewes (9% to 33%). Of 89 sera received from persons and 7 species of animals on the ranch, 44 (49%) were found to be seropositive to T gondii, including seropositive members of a family of 6. The rancher's wife and teenage daughter, both of whom were involved with lambing, had serum titers exceeding 4,096. Other members of the family not involved with lambing were seronegative by the indirect hemagglutination test. The 2 infected persons are known to have come in contact with placentas, birth fluids, fetuses, and colostrums from these infected ewes.