Search

Pestiviruses are enveloped single-chain ribonucleic acid viruses with a positive polarity. Pestiviruses include the viruses of classical swine fever (hog cholera), Border disease of sheep, mucosal disease of cattle, and isolates obtained from wild animals, such as red deer (Cervus elaphus). Among ruminants, pestiviruses have developed a remarkable strategy for assuring their persistence. Through epigenetic transmission, they lead to the birth of asymptomatic carrier animals harbouring non-cytopathic variants, which become immunotolerant to the strain of virus present. The presence of a small number of asymptomatic carriers enables the virus to circulate within a herd by horizontal transmission, leading to the birth of a new generation of asymptomatic carriers.

The incidence of delta infections in Morocco has been investigated to explain the high rate of severe hepatitis B (HB) observed in this country. The presence of delta antigen (D Ag) and antibodies to delta agent (D Ab) was tested by radio-immuno-assay in the sera from 85 HBs Ag positive patients, hospitalized in Casablanca: among them 57 suffered from acute or fulminant HB (12 deceased), 10 from chronic hepatitis and 18 from cirrhosis. Neither D Ag nor D Ab were found, excepted once in a patient with cirrhosis having shown the presence of D Ab. In contrast with the high endemicity of delta agent reported in other countries of North Africa, the incidence of delta infections seems to be very low in Morocco.

The prevalences of HBs Ag and HBs Ab were investigated among 221 hospital or laboratory staffs in Casablanca (Morocco) to estimate the importance of risks of infection by HBV at which they were exposed with regard to a control group including 195 blood givers from the city. Staff originated from following departments: infectious diseases, emergency, blood center, haemodialysis and a laboratory associated to this one. HBs Ag has been investigated by inhibition of haemagglutination and HBs Ab by passive haemagglutination. X2 test, with Yates correction if need, was used as statistical. method. HBs Ag and Ab prevalences, higher among hospital staff than in controls (p less than 0.05), showed an increased risk of HBV infection in the formers. Among staff, whatever one's occupation may be, HBs Ab prevalence did not shown appreciable changes. In contrast, the HBs Ag one varied significantly from one department to the other, depending on factors such as hygiene and asepsis, reducing the risk, and contagiousness of some hospitalized patients or more or less frequent exposures to infectious blood, increasing the risk. The influence of these factors was illustrated and discussed by comparison of HBs Ag prevalence with frequency or importance of infectious exposures among staff from each studied department. As reported in various countries, in Morocco hospital and laboratory staff is exposed to a high risk of infection by HBV and the interest to vaccine such persons against hepatitis B is underlined.

The effect of prostaglandins PGE2 and PGF alpha 2 on infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus 1; BHV-1) was studied by using the measurement of the mean size of plaques produced in cell culture by IBR/Cu5 strain. Three concentrations (0.1, 1 and 10 micrograms/ml) of prostaglandins, PGE2 and PGF alpha 2 were used. Each prostaglandin provoked an increase in the mean plaque size when compared to control plaques, at the concentrations 1 and 10 micrograms/ml for PGE2 and 10 micrograms/ml for PGF alpha 2.