Bovine ephemeral fever virus triggers autophagy enhancing virus replication via upregulation of the Src/JNK/AP1 and PI3K/Akt/NF-κB pathways and suppression of the PI3K/Akt/mTOR pathway.

Autophagy plays an important role in cellular response to pathogens. However, the impact of the autophagy machinery on bovine ephemeral fever virus (BEFV) infection is not yet determined. A recent study in our laboratory demonstrated that BEFV triggers simultaneously the PI3K/Akt/NF-κB and Src/JNK-AP1 pathways in the stage of virus binding to enhance virus entry. In this work, we report that BEFV induces autophagy via upregulation of the PI3K/Akt/NF-κB and Src/JNK/AP1 pathways in the early to middle stages of infection and suppresses the PI3K/Akt/mTOR pathway at the late stage of infection. To activate NF-κB, BEFV promotes degradation of IκBα and activates Akt to stimulate NF-κB translocation into the nucleus. Immunoprecipitation assays revealed that BEFV disrupts Beclin 1 and Bcl-2 interaction by JNK-mediated Bcl-2 phosphorylation, thereby activating autophagy. Overexpression of Bcl-2 reversed the BEFV-induced increase in the LC3 II levels. Suppression of autophagy either by knockdown of autophagy-related genes with shRNAs or treatment with a pharmacological inhibitor 3-MA reduced BEFV replication, suggesting that BEFV-induced autophagy benefits virus replication. Our results revealed that the BEFV M protein is one of the viral proteins involved in inducing autophagy via suppression of the PI3K/Akt/mTORC1 pathway. Furthermore, degradation of p62 was observed by immunoblotting, suggesting that BEFV infection triggers a complete autophagic response. Disruption of autophagosome-lysosome fusion by depleting LAMP2 resulted in reduction of virus yield, suggesting that formation of autolysosome benefits virus production.

Observations on the recent epizootic of bovine ephemeral fever in Saudi Arabia.

Observations of the epizootic of bovine ephemeral fever which occurred in Saudi Arabia during 1996 are presented. The investigations included the collection of epidemiological data from affected farms and the testing of sera for antibodies to the virus. The authors report a mean morbidity rate of 50% and a mean case fatality rate of 0.3%. Of the infected cattle, 4% were affected by recumbency, the majority of these recovered (89%). The clinical signs observed in affected cattle were uniform throughout the region concerned. The features of the outbreak, obtained through field investigations, were considered in relation to the ecological and meteorological conditions which were prevalent at the time. The outbreak occurred during the summer months (May to October) in the central and eastern regions of Saudi Arabia, with the initial infection reported at the Al-Ahsa oasis. Farms which were subsequently affected were all reported to possess areas of stagnant water suitable for the reproduction of the vectors of the disease (Culicoides spp. and mosquitoes). To conclude, the authors discuss precautions to prevent future outbreaks of bovine ephemeral fever in Saudi Arabia.

Evaluation of the effect of ketoprofen on experimentally induced ephemeral fever in dairy heifers.

OBJECTIVE: To evaluate ketoprofen for the therapy of ephemeral fever. DESIGN: A blind controlled clinical trial. ANIMALS: Sixteen cattle (one immature Holstein bull, eight Holstein and seven Jersey heifers). PROCEDURE: Ephemeral fever was induced by the intravenous injection of blood leucocyte layer from a clinical case. Ketoprofen solution or a coded placebo was injected intramuscularly at the rate of 3 mg/kg daily for three days. RESULTS: Ketoprofen reversed locomotor dysfunctions significantly compared with controls, but did not have any effect on rectal temperatures, leucocyte counts, plasma fibrinogen concentrations, ionised Ca-concentrations or the presence of dyspnoea. CONCLUSION: Ketoprofen is a safe and effective drug for the treatment of locomotor symptoms of milk fever, but has no effect on the duration of clinical respiratory abnormalities.

Studies on the pathogenesis of bovine ephemeral fever. IV: A comparison with the inflammatory events in milk fever of cattle.

The study of ephemeral fever in cattle has defined a range of haematological and biochemical changes in blood which are characteristic of an inflammatory response. One of the clinical signs of ephemeral fever, a temporary paralysis reversible by treatment with calcium borogluconate, is similar to that in milk fever (parturient paresis), a disease of multiparous dairy cows. Three separate groups of cows were studied. Four multiparous cows were observed and sampled repeatedly during calving, three similar cows and one cow calving for the first time in a dairy herd were sampled daily before and after calving; and, in other dairy herds, seven cows with milk fever were sampled during illness. One of the cows under repeated observation during calving developed milk fever. The results showed that all the inflammatory indicators in blood were present in the multiparous cows at calving and that these were essentially similar to those established in ephemeral fever. The similarities in the four cows sampled repeatedly during the periparturient period were: a rectal temperature rise of 1 to 1.2 degrees C; rise in circulating neutrophils to peaks between 5700 and 11200 l-6; disappearance of eosinophils for 1 day; hypocalcaemia (plasma Ca < 2.0 mM l-1); fall of plasma zinc to low levels immediately after calving (plasma Zn < 500 micrograms l-1); fall of inorganic phosphate (plasma P < 0.9 mM l-1); rises in copper (plasma Cu > 1000 micrograms l-1) and plasma fibrin to > 8.75 g l-1. Plasma glucose peaked at calving between 5.7 and 8.9 mM l-1 then fell to levels ranging between 3.4 and 3.8 mM l-1. Plasma iron rose in one cow to 1220 micrograms l-1, was unchanged in one cow and fell in the other two to 440 and 860 micrograms l-1 respectively. The three multiparous cows which were sampled daily and calved normally showed similar haematological, macro and micromineral changes and fibrin response as did the seven milk fever cases. In the periparturient period, milk fever cows differed from multiparous cows calving normally, in degree but not in kind, of inflammatory response. It is postulated that an inflammatory event occurs in the periparturient period of multiparous cows which partially accounts for the falls in plasma calcium. This can precipitate a paralysis and other hypocalcaemic signs similar to that seen in acute ephemeral fever.