Confirmation of vertical transmission of bovine immunodeficiency virus in naturally infected dairy cattle using the polymerase chain reaction.

The purpose of this study was to determine whether bovine immunodeficiency virus (BIV) is vertically transmitted in naturally infected dairy cattle. Twenty-two dam/calf pairs from a Mississippi Agriculture and Forestry Experiment Station dairy were the study group. Blood samples were collected following delivery of calves, the peripheral blood leukocytes were purified from these samples, and the leukocyte DNA was used in polymerase chain reactions targeting the pol gene region of the BIV provirus. Southern blotting and hybridization were used to confirm the BIV specificity of the amplified fragments. BIV provirus was detected in 14 of 22 calves (64%), demonstrating vertical transmission. Eight of the calves were disqualified from the final interpretation of transplacental transfer because they may have nursed their mothers prior to blood collection, allowing the possibility of lactogenic transfer of the virus. Transplacental transmission of BIV was identified in 6 of 22 calves (27%).     

Detection of early embryonic development in chicken eggs using visible light transmission

1. In two separate experiments, the possibility of detecting embryonic development in chicken eggs was assessed using the same spectrophotometric method used to detect blood in Table eggs, using a combination of two wavelengths (577 and 610 nm) of the transmission spectrum. 2. In the first experiment, during the first 10 d of incubation, transmission spectra of 30 Hisex White eggs and 30 Hybro eggs were measured daily. 3. In the second experiment, 292 Hisex White eggs were incubated. Seven groups were randomly assigned. Six received an injection of sodium azide (NaN3) at different times during incubation in order to stop embryonic development, and during the first 12 d of incubation the transmission spectrum was measured daily. The acoustic resonance analysis method was also used on a group of uninjected eggs. 4. In the first experiment, it was possible to detect embryonic development from 120 h of incubation onwards in fertile eggs. In the second experiment changes in light transmission due to embryonic development were detected from 108 h of incubation. Detection of embryonic development using the acoustic resonance analysis method in the second experiment was possible only from 120 h of incubation. 5. It was concluded that the detection of embryonic development using visible light transmission is not directly linked with the formation of blood, but with the formation of sub-embryonic fluid, which takes place from 72 h of incubation onwards. This fluid makes the yolk sac translucent so that absorption of light at 577 nm can be detected.     

Effect of tapered normal and interval training on performance of Standardbred pacers

Human athletes taper or reduce their training load before a race to enhance performance, apparently because recovery from the effects of fatigue occurs faster than the loss of fitness from the reduced training. However, there appear to be no previous studies of tapering of equine athletes. Our aim in the present study was, therefore, to investigate the efficacy of tapering with Standardbred pacers. We determined the effect of repeated cycles of tapered training on performance of Standardbred pacers. After 8 weeks of jogging and 3 x 2 week cycles of pace work, 19 horses were randomised to a taper and a control group. The taper group completed 5 consecutive 2 week cycles, each incorporating a 7 day taper; some cycles included high-intensity interval training. The control group continued with 5 more cycles of pace work. All horses completed a 2400 m individual time trial after each cycle. Peak and mean speed of the taper group were faster than those of the control group in all cycles; the differences were clear-cut in all cycles for peak speed (overall 4.4%, 95% confidence interval 1.7 to 7.1%), but only in one of the interval-training cycles for mean speed (2.4%, 0.3 to 4.7%). Four horses in the taper group were injured during interval training. Repeated tapering produces a worthwhile enhancement of performance in Standardbreds, but the addition of interval training appears to increase the risk of injury.     

Identification of monoclonal antibodies that cross-react with cytokines from different animal species

Eleven monoclonal antibodies specific for ovine, bovine and human cytokines were investigated by flow cytometry for cross-reactivities with cytokines produced by peripheral blood mononuclear cells (PBMCs) from sheep, cattle, goat, swine, horse, dog, mink, rabbit and human. Four antibodies specific for IL-4, IL-8, IFN-gamma and TNF-alpha cross-reacted with cytokines from a majority of the species investigated. These antibodies can be applied to flow cytometric studies of cytokine production by PBMCs from several veterinary species. Another five antibodies specific for IL-2, IL-6, GM-CSF and IFN-gamma (two antibodies) cross-reacted weakly and with a variable number of animal species. These antibodies could in certain situations be useful in flow cytometry. In a number of cases the immunological cross-reactivities were confirmed by Western blot analyses. Overall, the results of this study will remedy some of the lack of species-specific anti-cytokine antibodies in veterinary research.     

Mice immune responses to Brucella abortus heat shock proteins. Use of baculovirus recombinant-expressing whole insect cells,purified Brucella abortus recombinant proteins,and a vaccinia virus recombinant as immunogens

Brucella abortus resists the microbicidal mechanisms of macrophages, and the expression of its heat shock proteins (HSPs) such as GroEL, GroES and HtrA may play a role in this resistance. Bacterial HSPs can be very immunogenic, inducing protective immunity in various types of bacterial infections. However, the significance of immune responses directed against B. abortus HSPs in the protection against brucellosis is currently unresolved. To elucidate the role of these proteins in protection against Brucella challenge, individual, divalent or trivalent baculovirus (BV) recombinants of B. abortus GroEL, GroES and/or HtrA were injected into BALB/c mice either as protein-expressing whole cells or as purified proteins. The preparations were given to mice in combination with Freund's or Ribi adjuvant, respectively. In addition, some mice were primed with a vaccinia virus-GroEL recombinant, followed by inoculation with purified GroEL-Ribi adjuvant combination. Antibodies were observed against B. abortus GroEL and HtrA, but not against GroES. Cellular immune response was demonstrated by observing significant IFN-gamma release by lymphocytes of mice immunized with the purified HtrA-Ribi adjuvant combination. However, none of the mice inoculated with individual, divalent or trivalent HSP-expressing cells combined with complete Freund's adjuvant or inoculated with purified B. abortus HSPs combined with Ribi adjuvant, were protected against challenge with B. abortus virulent strain 2308. Priming with vaccinia virus-GroEL recombinant and boosting with GroEL-Ribi combination did not induce protective immunity. Based on the results obtained, we suggest that although humoral and cell-mediated immune responses are induced, but protective immune response is not induced by B. abortus HSPs.     

Disposition kinetics of tylosin administered intravenously and intramuscularly to pigs

The distribution of tylosin was studied using a crossover design, in six pigs following i.v. and i.m. administration of 10 mgkg(-1) b.w. Plasma samples were analysed by HPLC and UV absorbance detection. After i.v. administration, t(1/2beta) was 271.3 min, V(d) 14.6 Lkg(-1), V(ss) 9.7 Lkg(-1) and CL 26.8 mLmin(-1)kg(-1). After i.m. administration, a C(max) of 1 microgmL(-1) was reached at 90 min. Mean absorption time was 1988.7 min and bioavailability was 95%.     

A cross-sectional coprological survey of liver flukes in cattle and sheep from an area of the southern Italian Apennines

A cross-sectional coprological survey of liver flukes (Fasciola hepatica and Dicrocoelium dendriticum) was conducted on 81 bovine farms and 197 ovine farms with animals pasturing in an area (3971 km(2)) of the southern Italian Apennines. The farms were selected to be uniformly distributed throughout the study area using geographical information system (GIS) software. Between June 1999 and March 2000, faecal samples were collected from 975 cattle and 3940 sheep and examined using a modified McMaster technique. The results were subjected to statistical analysis and point distribution maps (PDMs) were drawn by GIS.Cattle of 9 of the 81 (11.1%) farms were positive for F. hepatica and of 43 (53.1%) for D. dendriticum. Sheep of 8 of the 197 (4.1%) farms were positive for F. hepatica and of 133 (67.5%) for D. dendriticum. Co-infection was found in cattle of 2 (2.5%) farms, and in sheep of 8 (4.1%) farms.The findings of the present survey show that D. dendriticum was the predominant liver fluke found in cattle and sheep with respect to egg count numbers for both farms and animals. In addition, the general trends of the PDMs show that D. dendriticum was widely and homogeneously spread throughout the study area, whereas F. hepatica was present only in a few concentrated zones of the study area that had both positive bovine and positive ovine farms.     

Hosts,seasonal occurrence and life cycle of Rhipicentor nuttalli (Acari: Ixodidae)

There are only two species worldwide within the genus Rhipicentor, namely Rhipicentor bicornis and Rhipicentor nuttalli and both occur only in Africa. Rhipicentor nuttali has a widespread distribution in South Africa and the present investigation was initiated to elucidate its host preference, seasonality and life cycle. Rock elephant shrews, Elephantulus myurus were examined for ticks at four localities in the Free State Province, one in Gauteng Province and two in Limpopo Province, South Africa. Cape elephant shrews, Elephantulus edwardii were examined at two places in the Western Cape Province, and a single specimen of the bushveld elephant shrew, Elephantulus intufi was examined in central Namibia. Small mammals of other species were also examined at two of these localities. The majority of E. myurus at two sites in the Free State, at the locality in Gauteng and both sites in Limpopo Province were infested with larvae and/or nymphs of R. nuttalli, while the single E. edwardii examined at one site in the Western Cape Province and the single E. intufi examined in Namibia were infested with nymphs of this tick. Not one of the other small animals was infested. Although larvae and nymphs of R. nuttalli were present on E. myurus throughout the year, the former were generally most numerous during the period March to September, and the latter during May to October. The preferred hosts of the adults are domestic dogs, leopards, Panthera pardus and South African hedgehogs, Atelerix frontalis. Adult females engorged on Atelerix frontalis in 16-32 days and, after a preoviposition period of 2-4 days, produced approximately 170,00 eggs during the following 60-70 days. The average incubation period of the eggs was 59 days. Larvae engorged on E. myurus in 4-10 days and moulted to nymphs 12-20 days later. Nymphs required 11-15 days to engorge on E. myurus and moulted to adults 32-47 days later. Allowing 14 days for the exoskeletons and mouthparts of each of the three parasitic stages to harden before they can attach to a host, the life cycle took approximately 214 days to complete in the laboratory. The length of this period, considered in conjunction with the times of maximum seasonal occurrence of the immature stages, indicates that the life cycle probably takes a year to complete in the field.