NKp46 defines ovine cells that have characteristics corresponding to NK cells

ABSTRACT: Natural killer (NK) cells are well recognized as playing a key role in innate immune defence through cytokine production and cytotoxic activity; additionally recent studies have identified several novel NK cell functions. The ability to study NK cells in the sheep has been restricted due to a lack of specific reagents. We report the generation of a monoclonal antibody specific for ovine NKp46, a receptor which in a number of mammals is expressed exclusively in NK cells. Ovine NKp46+ cells represent a population that is distinct from CD4+ and γδ+ T-cells, B-cells and cells of the monocytic lineage. The NKp46+ cells are heterogenous with respect to expression of CD2 and CD8 and most, but not all, express CD16 - characteristics consistent with NK cell populations in other species. We demonstrate that in addition to populations in peripheral blood and secondary lymphoid organs, ovine NKp46+ populations are also situated at the mucosal surfaces of the lung, gastro-intestinal tract and non-gravid uterus. Furthermore, we show that purified ovine NKp46+ populations cultured in IL-2 and IL-15 have cytotoxic activity that could be enhanced by ligation of NKp46 in re-directed lysis assays. Therefore we conclude that ovine NKp46+ cells represent a population that by phenotype, tissue distribution and function correspond to NK cells and that NKp46 is an activating receptor in sheep as in other species.     

Bleomycin chemotherapy for metastatic squamous cell carcinoma in a ferret.

Bleomycin, an antitumor antibiotic, was effective in temporarily reducing the size of a metastatic squamous cell carcinoma in a ferret. The tumor had recurred after previous excision and had metastasized to the right submandibular lymph node. The ferret was treated without effect at a dosage of 10 U/m2, sc, once a week. The dosage was increased to 20 U/m2 once a week, and reduction of tumor size was observed.     

Economics of a dry-cow anthelmintic drenching programme for dairy cows in New Zealand. Part 2. Influence of management factors and other herd characteristics on the level of response

The results of a series of trials conducted on 47 seasonal supply dairy farms in the southern North Island of New Zealand, which indicated a statistically significant overall production response of 2.24 kg milkfat/cow/lactation following a 2-treatment dry-cow anthelmintic drenching programme (Bisset et al., 1987), were subjected to further analyses in an attempt to identify any management factors or herd characteristics which may have influenced the levels of production response to treatment in individual herds. The management factors examined included calf drenching practices, types of grazing system, mean pre-calving condition of the herds, and 'nutritional status' of the herds over the milking season. The influence of herd quality, herd size and geographical location were also examined. Considered separately, only calf drenching practice had a significant influence on the level of herd response to treatment. Increases in milkfat production/cow due to the treatment programme were significantly greater (P less than 0.05, t-test) on farms where calves had received a minimal number of drench treatments (less than or equal to 2) between weaning and the end of March (mid-autumn) (+5.32 kg/cow/lactation, P less than 0.01) (= 108.2 l milk), than on farms where calves had received regular 3-4 weekly treatments over the same period (+0.42 kg/cow/lactation, N.S.) While none of the other factors, considered in isolation, appeared to significantly influence the production response of herds, observations on possible interactive effects suggested that the grazing system employed was probably of importance in so far as it determined the level of exposure of cows to calf-contaminated pasture. Thus, the greatest mean response to the treatment programme occurred in herds where cows were overwintered on areas grazed during the milking season by calves which had received less than or equal to 2 drench treatments from weaning until the end of March (+5.95 kg milkfat/cow/lactation, P less than 0.01).     

Prenatal and preweaning deaths caused by pseudorabies virus and porcine parvovirus in a swine herd

Sequential outbreaks of pseudorabies virus and porcine parvovirus infections were documented at a swine farm in southern Minnesota. Data for the prevalence of mummified fetuses born and the preweaning mortality were recorded over a 3-year-period. The farm was a farrow-to-finish facility, with breeding females housed in 4 groups according to their stage of pregnancy. The herd consisted of approximately 130 breeding females in December 1981, and expanded to 220 females during the 12 months of 1982. Excluding the outbreaks, the mean preweaning mortality was 20.43% (SE 1.59) and the number of mummified fetuses per litter was 0.19 (SE 0.01). An outbreak of porcine parvovirus infection caused the preweaning mortality and number of mummified fetuses to increase to 50% and 4.10 per litter, respectively. Two outbreaks of pseudorabies 27 months apart, caused the preweaning mortality to increase to 95% and 82%, and the number of mummified fetuses to increase to 0.96 and 1.25 mummified fetuses per litter, respectively. The increase in mummification was observed 1 month after the increase in preweaning mortality caused by pseudorabies virus infections, whereas the increase in mummification and preweaning mortality was simultaneous with porcine parvovirus infections.     

Pig herds having a single reactor to serum antibody tests to Aujeszky's disease virus.

The introduction of Aujeszky's disease virus into a herd of pigs usually results in a rapid spread of the virus and a high percentage of pigs become seropositive. However, herd monitoring for the virus occasionally reveals a single seropositive breeding pig, referred to as a single reactor. The seropositive status of single reactors may be due to previous vaccination against Aujeszky's disease, or to exposure to a field strain of the virus, or to a false positive reaction in the serological assay. During a monitoring programme in Minnesota, 30 pig herds with single serological reactors were detected. Twenty-seven of these single reactors from 19 herds were segregated from their herds immunosuppressed with dexamethasone. Aujeszky's disease virus was isolated from four of the 27 pigs. Three of the four herds subsequently had outbreaks of Aujeszky's disease, suggesting that some single reactors were infected with Aujeszky's disease virus and had the potential to spread the virus within and between herds.     

Risk factors for mortality in grow-finishing pigs in Belgium

The present study investigated risk factors for mortality in grow-finishing pigs of 137 pig herds belonging to one integration company during a period of 2.5 years. Mortality data, expressed as the number of dead pigs divided by the number of pigs placed in the fattening unit were investigated retrospectively. The following potential risk factors were evaluated: type of pig herd, season and year of placement in the fattening unit, pig density in the municipality, management practices (density of the pigs in the barn, origin of the pigs), housing conditions and feeding practices. The overall average mortality percentage was 4.70%. Three variables in a multivariable regression model were significantly associated with mortality: season of placement in the fattening unit, origin of the piglets and duration of the fattening period. Pigs placed in October, November and December, were at higher risk than pigs placed in other months. Herds that purchased pigs from a merchant, used pigs from other herds with an excess of piglets for filling their fattening units or herds that purchased pigs from more than five origin herds also suffered higher mortality. The mortality also increased in case of longer duration of the fattening period. This study documented for the first time that in addition to seasonal effects and a longer duration of the fattening period, purchasing feeder pigs from one or a limited number of herds is of crucial importance to achieve low mortality in the grow-finishing pigs.     

Mother–Offspring Interactions in Zebu Cattle

The knowledge of the interaction between mother and offspring might contribute to enhance the welfare of the offspring and to improve the reproductive efficiency of the cow. However, there is still little information available about such interaction in some cattle breeds. A series of observational studies were set up, addressing the mother–offspring relationships of Nelore, Guzerat and Gyr cattle breeds. Firstly, the behaviour of cows and calves around the time of parturition was described, and then, the underlying factors that affect the calves' survival and development were studied. Special attention was given to the failure or delay in the first suckling. The results together are indicative of genetic variability for some studied variables, indicating the possibility of selection for calf vigour (using latency to stand up and latency to suckle as its indicators) and maternal ability (using percentage of time in contact with the calves), in spite of the estimates of heritability were low and presented high standard deviation for all variables. The individual variability in their suckling behaviour and the efficiency in first suckling cannot be explained by a single isolated underlying factor. By now, there are some results available, although there are many questions without answers. The field is still open for the development of future research.