Effects of bovine respiratory disease viruses and isoprinosine on bovine leukocyte function in vitro

Peripheral blood mononuclear cells obtained from 4- to 6-month-old-calves were inoculated in vitro with bovine herpesvirus-1, parainfluenza-3, or bovine virus diarrhea viruses. No increase in infectious virus progeny was observed; however, the viruses were detected in the cells for at least 96 h post-infection without any significant reduction in cell viability. The three viruses, either alone or in combination, suppressed phytohemagglutinin-induced proliferation of the mononuclear cells. The greatest suppression was observed in cultures inoculated with bovine virus diarrhea virus. Addition of isoprinosine partially restored this viral-induced suppression of proliferative response, and the efficiency of reversal was greater in bovine virus diarrhea virus-infected cells. Interleukin-2 activity was higher in cultures of virus-infected mononuclear cells than in cultures of non-infected cells.     

Heat stress effects on livestock: molecular,cellular and metabolic aspects,a review

Elevated ambient temperatures affect animal production and welfare. Animal's reduced production performances during heat stress were traditionally thought to result from the decreased feed intake. However, it has recently been shown that heat stress disturbs the steady state concentrations of free radicals, resulting in both cellular and mitochondrial oxidative damage. Indeed, heat stress reorganizes the use of the body resources including fat, protein and energy. Heat stress reduces the metabolic rates and alters post‐absorptive metabolism, regardless of the decreased feed intake. Consequently, growth, production, reproduction and health are not priorities any more in the metabolism of heat‐stressed animals. The drastic effects of heat stress depend on its duration and severity. This review clearly describes about biochemical, cellular and metabolic changes that occur during thermal stress in farm animals.     

Bovine herpesvirus-1 and parainfluenza-3 virus interactions: clinical and immunological response in calves.

Calves infected with bovine herpesvirus-1 (BHV-1) or both BHV-1 and parainfluenza-3 virus (PIV-3) developed clinical signs including fever, cough, and nasal and ocular discharges. Animals infected with both viruses appeared more depressed and showed higher rectal temperature, while calves inoculated with PIV-3 alone had a very mild clinical disease. Both BHV-1 and PIV-3 were recovered from nasal secretions up to six to eight days postinoculation. However, the virus titers were lower in calves with mixed infection. An increase in serum antibodies to both BHV-1 and PIV-3 was detected by serum neutralization and enzyme-linked immunosorbent assay. Antibody responses were delayed and significantly lower in calves given mixed infection than in calves infected with a single virus. Interleukin-2 activity in cultures of lymphocytes from BHV-1 and BHV-1 plus PIV-3 infected calves was higher compared to control calves.     

First serological investigation of peste-des-petits-ruminants and Rift Valley fever in Tunisia

This study, carried out between September 2006 and January 2007, is the first cross-sectional serological investigation of peste-des-petits-ruminants (PPR) and Rift Valley fever (RVF) in Tunisia. The objective was to assess the potential need to develop a dual, recombinant PPR–RVF vaccine and how such a vaccine might be utilised in Tunisia. An overall PPR seroprevalence of 7.45% was determined, a finding supported by the high specificity (99.4%) and sensitivity (94.5%) of the ELISA used. On assessment of the diversity and density of mosquitoes in the sampling area, four species of RVF-vectors of the genus Aedes and Culex were identified. However, no serological evidence of RVF was found despite the use of a highly sensitive ELISA (99–100%). Larger scale investigations are underway to confirm these findings and the continuation of the emergency vaccination program against these two diseases remains valid.     

Propagation of infectious bovine rhinotracheitis (bovine herpes-1) virus in murine primary cell cultures

Virus synthesis in BALB/C mouse lung and kidney primary cultures infected with infectious bovine rhinotracheitis (IBR) virus started between 6 and 8 hours after virus inoculation and reached a maximum titer of 5.5 log₁₀ plaque forming units (PFU) at 48 hours postinfection (PI). Cytopathic effect (CPE) in cell cultures occurred at 8–10 hours and over 90% of the cells had CPE by 48 to 72 hours PI. The bulk of the newly replicated virus (60–80%) was cell-associated as determined by plaque assay of extracellular and intracellular virus. Pulse-chase experiments demonstrated incorporation of radioactive precursors into viral DNA and protein macromolecules. Viral DNA synthesis was initiated between 2 and 4 hours PI and was maximum at 4 to 6 hours. Viral proteins were detected at 4 hours and peaked between 6 and 8 hours PI. Enzyme-linked immunosorbant assay (ELISA) confirmed synthesis of specific viral proteins, which gradually increased during the virus growth cycle. Abstract in French is given at the end of the article.

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Resume La synthèse du virus de la rhinotrachéite infectieuse bovine (virus IBR) sur des cultures primaires de poumon et de reins de souris (souche Balb/C) commençait entre 6 et 8 heures après inoculation du virus et atteignait un titre maximal de 5.5 log PFU (Plaque Forming Unit) 48 heures après infection. L'effet cytopathogenic (CPE) sur ces cultures cellulaires apparaissaient en 8 à 10 heures et plus de 90% des cellules montraient un CPE en 48 à 72 heures après infection. La détermination par la méthode des plages sous agarose, du virus extracellulaire et du virus intracellulaire, indiquait que 60–80% du virus synthétisé était associé avec les cellules. Les expériences de pulsechase demontraient l'incorporation des précurseurs radioactifs dans les protèines et ADN viraux. La synthèse virale d'ADN était initiée entre 2 et 4 heures après infection et était maximale en 4 à 6 heures. Les protéines virales étaient détectées en 4 heures avec un maximum de synthèse entre 6 et 8 heures après infection. Enzyme-linked immunosorbant assay (ELISA) confirmait la synthèse de protéines virales spécifiques qui montrait une augmentation graduelle pendant le cycle de replication du virus.

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Supported in part by grants 0831 from the Cooperative State Research Service of the US Department of Agriculture and published as contribution 85-160-J, Kansas Agricultural Experiment Station.