Experimental transmission of bovine papilloma virus (BPV) extracted from morphologically distinct teat and cutaneous lesions and the effects of inoculation of BPV transformed fetal bovine cells.

Bovine papilloma virus (BPV) was extracted from five cattle each affected with only one of five morphologically distinct lesion types. When inoculated into experimental calves either by scarification or intradermal injection, the BPV extracts produced lesions macroscopically and microscopically similar to those from which individual extracts were made. Fetal bovine cells, transformed in vitro with BPV, failed to produce fibromas, fibropapillomas or papillomas when inoculated into experimental calves. When calves inoculated with virus or BPV transformed cells were challenged with the five original BPV extracts, a differential immunity was demonstrated, while control calves were susceptible to all extracts. Post mortem examination revealed the presence of upper alimentary tract papillomas in three of eight calves forming one group. These results suggest that different strains of BVP, causing morphologically separable lesion types, exist. There may be additional BPV variants causing fibropapillomas of the teat and anogenital regions of cattle. The inoculation of BPV transformed fetal bovine cells conferred a relative immunity to later challenge with some but not all BPV extracts.     

Serological characteristics of affected cattle during an outbreak of bovine enzootic encephalomyelitis caused by Akabane virus

During an outbreak of bovine enzootic encephalomyelitis caused by the Akabane virus (AKAV) in 2010, 210 serum samples were collected from the affected cattle, and serological investigations for the AKAV were performed using a serum neutralization test (SNT) and an enzyme-linked immunosorbent assay (ELISA). The seropositive rates for SNT and ELISA were 90.0 and 85.2 %, respectively. The titers of SNT (log₂) against the AKAV were higher than 4.0 in the highly affected cattle (80.0 %). This finding indicates that most affected cattle were infected with the AKAV and that strong immune responses against this virus were elicited in affected cattle. The strong immune response to the AKAV in cattle may provide insight into the occurrence of bovine encephalomyelitis caused by the AKAV.     

An outbreak of tuberculosis in pigs and cattle caused by Mycobacterium africanum.

An outbreak of tuberculosis in pigs and cattle caused by Mycobacterium africanum produced lesions in the pigs similar to those caused by M tuberculosis, M bovis and M avium, with caseation in the lymph nodes of the head and in the jejunal lymph nodes. Bacteriological examination of the dysgonic mycobacteria isolated showed that they were M africanum I. The intradermal tuberculin test was very reliable in pigs, differentiating between mammalian and avian reactions, and the results of the test were in accordance with the lesions found at meat inspection. No clinical signs were observed during the outbreak, and the infection was neither serious nor progressive. There were no lesions in the tuberculin-positive cattle. The source of the infection remains unknown.     

Border disease in sheep caused by transmission of virus from cattle persistently infected with bovine virus diarrhoea virus.

Two outbreaks of border disease occurred on farms with sheep flocks and breeding cattle. The infection of the pregnant sheep was probably caused by transmission of virus from calves persistently infected with non-cytopathic bovine virus diarrhoea virus (BVDV) which were kept in close confinement with the ewes during mid-pregnancy. Border disease was also induced experimentally in eight lambs by exposing their dams at 38 to 78 days of gestation to a heifer persistently infected with BVDV. Both the natural and the experimental infections were characterised by typical signs such as 'hairy-shaker' lambs and high lamb mortality. The diagnosis was confirmed by virus isolations from live-born lambs, seroconversion and pathology. The study supports the assertion that cattle persistently infected with BVDV and in close contact with pregnant sheep, are an important source of strains of virus capable of causing border disease.     

Papillomatosis of the bovine teat (mammary papilla)

A 4th of 667 cattle examined at a Wisconsin abattoir had teat papillomas. Excised teat papillomas were sorted by gross morphologic characteristics into 3 groups: (i) atypical filiform, (ii) atypical flat, and (iii) typical fibropapilloma. Bovine papilloma virus capsid antigen was detected in thin-section slides of the 3 groups of teat papillomas by peroxidase-antiperoxidase assay. The bovine papilloma virus involved with the atypical papillomas could not be characterized by molecular hybridization, because enough pure virus could not be harvested. Homogenates of the 3 groups of teat papillomas were inoculated on 2 ponies and 4 calves. Typical fibropapillomas were produced on the 4 calves, and fibromas, on the 2 ponies. Atypical papillomas were produced only in 2 heifers.     

Respiratory disease caused by Mycoplasma bovis is enhanced by exposure to bovine herpes virus 1 (BHV-1) but not to bovine viral diarrhea virus (BVDV) type 2

To determine if previous exposure to bovine viral diarrhea virus (BVDV) and bovine herpes virus 1 (BHV-1) type 2 affects the onset of disease caused by Mycoplasma bovis, 6- to 8-month-old beef calves were exposed to BVDV or BHV-1 4 d prior to challenge with a suspension of 3 clinical isolates of M. bovis. Animals were observed for clinical signs of disease and at necropsy, percent abnormal lung tissue and presence of M. bovis were determined. Most animals pre-exposed to BHV-1 type 2 but not BVDV developed M. bovis-related respiratory illness. In a second trial, we determined that a 100-fold reduction in the number of M. bovis bacteria administered to BHV-1 exposed animals reduced the percentage of abnormal lung tissue but not the severity of clinical signs. We conclude that previous exposure to BHV-1 but not BVDV type 2 was a necessary cause of M. bovis-related respiratory diseases in our disease model.     

Detection of bovine viral diarrhea virus (BVDV) in seropositive cattle

Detection of bovine virus diarrhoea virus (BVDV) in one vaccinated beef cattle and three non-vaccinated dairy herds was investigated on peripheral blood leukocytes (PBL) with or without previous treatment followed by a capture ELISA (cELISA). Using the combination of PHA and polycation treatment, PBL from 229 seropositive cattle were studied and could be classified in four different states of BVDV infection. Lysed PBL from four animals were directly positive in cELISA (Category I), PBL of 17 animals were positive after PHA stimulation (Category II), 15 animals were positive only after PHA stimulation plus polycation treatment (Category III), while virus could not be detected in 193 seropositive cattle. Wild-type BVDV strains were isolated by co-culture on polycation-treated MDBK cells from 11 of these seropositive animals. BVDV antibodies of these same animals were able to neutralize their own virus, indicating that virus persists in PBL in spite of strain-specific antibodies. No apparent change of leukocyte subpopulations could be detected in any category of virus-positive animals. Thus, BVDV may be present in the PBL of some cattle, even in the presence of a specific active immune response.     

An outbreak of haemorrhagic septicaemia (septicaemic pasteurellosis) in cattle in Zimbabwe

Summary An outbreak of haemorrhagic septicaemia caused byPasteurella multocida in beef cattle in Zimbabwe grazing effluent-irrigated pastures, is described. The outbreak occurred during the wet summer months and predisposing stress factors included excessive rainfall and unusual cold weather during the preceeding month. History, clinical features and post-mortem findings were consistent with reports of the disease from other countries, except that meningitis was also a constant feature. Morbidity approached 77% and mortality 5 per cent. Prophylactic treatment and vaccination with a killed bacterin together with a return of warmer and drier weather were probably important in halting the outbreak.

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Resumen Se describe un brote de septicemia hemorrágica en ganado bovino, causada porPasteurella multocida, en Zimbabwe El brote ocurrió durante los meses lluvisos de verano, los que se caracterizaron por precipitación pluvial excesiva y frío. La historia, síntomas clínicos y hallazgos posmortem, concuerdan con los descritos en otros países, excepto por la menigitis encontrada. La morbilidad fue de aproximadamente 77% y la mortalidad cinco por ciento. El tratamiento profiláctico instituído, la vacunación con bacterina y el retorno a la normalidad climática, fueron factores probablemente importantes para detener el brote.

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Résumé Les auteurs décrivent un début de septicémie hémorragique àPasteurella multocida dans un troupeau de boeufs, au Zimbabwé, paturant sur des prairies irriguées par des affluents. Le foyer s'est déclaré pendant les mois humides de l'été. Parmi les facteurs prédisposants et stressants, on a noté des chutes de pluies excessivement abondantes et un temps froid inhabituel durant le mois précédent. L'anamnèse, les aspects cliniques et les résultats des autopsies se sont révélés cohérents avec la relation de la maladie dans d'autres pays, à l'exception de la méningite qui s'est constamment manifestée. La morbidité a approché 77 p. 100 et la mortalité 5 p. 100. Un traitement prophylactique et une vaccination avec des bactéries tuées en même temps que le retour d'un temps plus chaud et plus sec ont probablement contribué à enrayer le foyer.