[Use of the immunoenzyme test ELISA-NS3 to distinguish horses infected by African horsesickness virus from vaccinated horses]. / Utilisation de l'épreuve immuno-enzymatique ELISA-NS3 pour différencier les chevaux infectés par le virus de la peste équine des chevaux vaccinés.

A vaccination protocol involving three horses, with five repeated injections of inactivated serotype 4 African horse sickness virus, was undertaken to determine a possible threshold for the appearance of antibodies against the non-structural protein NS3. Using an indirect enzyme-linked immunosorbent assay, with the recombinant NS3 protein as an antigen, the authors detected a response to NS3 as of the second injection for the first horse and after four injections for the second horse. No response to NS3 was detected for the third horse. The results show that the inactivated vaccine is insufficiently purified to eliminate the non-structural protein NS3. Therefore using the NS3 protein as a marker did not enable differentiation between vaccinated and infected horses.

Clinical, virological and immune responses of normal and immunosuppressed donkeys (Equus asinus africanus) after inoculation with African horse sickness virus.

To elucidate the role that donkeys may play in African horse sickness virus (AHSV) persistence during inter-epizootic periods we looked for clinical signs of infection and studied the viraemia and neutralising antibody kinetics in 3 immunocompetent and 3 immunosuppressed donkeys inoculated with AHSV-4. None of the donkeys developed signs of AHS. However infectious AHSV was isolated from the blood of the immunocompetent donkeys for up to 17 days post infection (dpi) and viral antigens were detected for up to 28 dpi. Immune cells also increased significantly from 35 to 60 dpi. There was no evidence of a recrudescence of viraemia following immunosuppression of these donkeys at 90 dpi despite a decrease in the numbers of immune cells. Infectious virus was not isolated from the blood of donkeys that had been immunosuppressed, prior to AHSV inoculation. However viral antigens were detected for up to 35 dpi. The titres of AHSV-specific neutralising antibodies and the number of immune cells were also significantly lower than in immunocompetent animals. Our findings suggest that donkeys may be able to play a role in the epidemiology of AHS but the ability of vectors to become infected by feeding upon viraemic donkeys needs to be assessed before the significance of that role can be fully understood.

[Epidemiology of diarrhea caused by Escherichia coli and rotavirus in calves and lambs in Morocco]. / Epidèmiologie des diarrhées à Escherichia coli et à rotavirus chez le veau et l'agneau au Maroc.

An epidemiological survey on E coli and rotavirus associated diarrheas in one to twenty five days old calves and lambs was made in three regions: Rabat-Kenitra, Marrakech and Agadir. Isolated E coli K99 stains have been studied of a biochemical, serotypical (O antigen) and antibiotypical point of view. The identification of rotavirus was made by ELISA test. Persistence of K99 antigen and heat stable toxin A was examined after a conservation of 5 weeks at - 18 degrees C. The frequency of E coli K99 or rotavirus associated diarrheas is respectively 26.9% and 29.7% in calf, 10% and 30% in lamb. This incidence considerably decreases from the 20th day in calf and from the 11th day in lamb. It must be observed that 34.8% of cases of diarrheas in calf and 55% in lamb cannot be ascribed to investigated agents. Only 12 out of 42 E coli K99 strains belong to serogroups O101, O8 and O9. Preservation of strains to - 18 degrees C comes with the loss of K99 antigen. These strains are not toxinogens. Among the strains having kept this antigen, 29% are toxinogens. Surveyings of antibiotics resistance was discussed.