Bovine mammary glands were inoculated intracisternally with a streptomycin-resistant (SR) strain of Corynebacterium bovis to determine the number of colony-forming units (CFU) required to induce colonization and to maintain persistence of C bovis colonization throughout lactation and involution. Streptomycin resistance was used as a strain marker. Uninfected quarters in cows during midlactation were challenge exposed with successively higher numbers of SR C bovis until all quarters became colonized. Inoculum containing 790 CFU of SR C bovis established colonization in only 7 of 38 quarters. Colonization persisted in only 4 of these quarters by 23 days after inoculation. Eleven quarters were reinoculated with higher numbers of SR C bovis, and all became colonized by the time challenge-exposure inoculum contained 8 X 10(4) CFU. Colonization persisted throughout the 93-day experimental period. Somatic cell counts were significantly (P less than 0.01) higher in SR C bovis-colonized quarters after inoculation than before. Sixteen additional quarters were inoculated with a mean number of 8 X 10(4) CFU of SR C bovis 7 days before suppression of lactation. All quarters became colonized, and SR C bovis was shed during the experimental period; throughout the nonlactating and peripartum periods, high numbers of SR C bovis in pure culture were shed from 13 of 16 quarters.

Eight adult cats were inoculated IV (n = 6) or SC (n = 2) with Ehrlichia risticii-infected P388Dl (continuous murine macrophage) cells or with E risticii released from P388D1 cells. Three additional cats were inoculated with organism-free P388D1 cultured monocytes, and 1 cat, which served as a medium control, was inoculated with balanced salt solution. Clinical signs of illness were observed in the IV inoculated cats from which E risticii was isolated. One cat developed intermittent diarrhea between postinoculation days (PID) 8 and 18, and the other cat developed lymphadenopathy, acute depression, and anorexia between PID 20 and 24. Ehrlichia risticii was isolated in cultures from 2 of 6 IV inoculated cats on PID 6, 10, and 17. Both cats were inoculated with E risticii released from the P388D1 cells. Ehrlichia risticii was not isolated from SC inoculated cats or from control cats. All 8 cats inoculated with E risticii seroconverted between PID 10 and 23. A pony inoculated with E risticii isolated from 1 of the inoculated cats developed clinical signs of equine monocytic ehrlichiosis including fever, anorexia, depression, and mild colic. Ehrlichia risticii was isolated from the blood of this pony on PID 7, 9, 11, and 16.

The relationship between histologic lesions in endometrial biopsy specimens and susceptibility to chronic uterine infection (CUI) in mares was investigated. Mares were allotted to 4 groups on the basis of degree of endometrial lesions. Mares in group 1 (n = 6) had no pathologic changes, mares in group 2 (n = 5) had only mild pathologic changes, group-3 mares (n = 7) had moderate changes, and group-4 mares (n = 7) had severe inflammatory and fibrotic endometrial changes. Susceptibility to CUI was determined by the inflammatory response to intrauterine inoculation of 5 X 10(6) Streptococcus zooepidemicus. The inoculum was given on the third day of behavioral estrus and in the presence of a follicle > 30 mm. Mares with > 1 neutrophil/5 high-magnification (400 X) microscopic fields and > 20 colonies of S zooepidemicus at 96 hours after inoculation were considered to be susceptible to CUI. There was a significant association between biopsy grade and susceptibility to CUI among the groups. Histologically normal endometrium was associated with resistance to CUI, and severe histopathologic changes in the endometrium were associated with susceptibility to CUI. Mild to moderate endometrial lesions did not correlate consistently with susceptibility or resistance to CUI.

Mx1 (Myxovirus resistance protein) and Oas1b (Oligoadenylate synthetase-1), induced by type 1 interferon (IFN), play a role in early antiviral innate immunity by inhibiting the replication of viruses. In mice, Mx1 and Oas1b confer resistance to the infection of orthomyxoviruses including influenza viruses and flaviviruses including West Nile viruses, respectively. Laboratory mice have been used to study the mechanisms of the pathogenesis of these virus infections; however, it is possible that they are not a suitable model system to study these viruses, since most of the inbred laboratory mouse strains lack both genes. It has been reported that feral mouse-derived inbred strains show resistance to the infection of these viruses due to the presence of intact both genes. In this study, we generated congenic strains in which the Mx or Oas locus of the MSM/Mx (MSM) mouse was introduced to the most widely used mouse strain, C57BL/6J (B6). B6.MSM-Ms mice showed resistance to the infection of influenza virus but not of West Nile virus. On the other hand, B6.MSM-Oas mice showed resistance to the infection of West Nile virus but not of influenza virus. Our results indicate that Mx1 and Oas1b show highly antiviral specificity in mice possessing the same genetic background. Therefore, these congenic mice are useful for not only infection study but also investigation of host defense mechanism to these viruses.

In the conditions of the Republic of Belarus there was analyzed fauna of parasites of gastro-intestinal tract and natural resistance of horses in the conditions of Polesye State Radiation Ecological Reserve. There were worked the most efficient antihelminthic compounds. Analysis of helminthological state showed that extensiveness helminthic and gastrophilosis invasion of horses was at a high level. In this regard the nematodosis and gastrophilosis (Gastrophilus intestinalis) invasions prevailed. In mature and growing horses there was marked the dominance of nematode worms of Strongylidae / Trichonematidae families (78,9-83,8%) and Gasterophilidae (95,8%). Next, at growing horses there were stated nematodes Strongyloides westeri and cestoid worms of Anoplocephalidae family, at mature horses – of Gasterophilidae, Parascaris equorum and Oxyuris equi families. The following antihelminthic compounds ans preparations showed the best efficiency: Univerm; Avermektin paste 1%; Fenbendazoli, Rivertin 1%.