Susceptibility of laboratory animals to experimental infection with Ife virus.

The susceptibility of rabbits, domestic chickens and albino rats to experimental infection with Ife virus was investigated. Neither pyrexia nor clinical signs of disease were observed in infected rabbits or chickens. Low-grade viraemia (10(1.0) mouse lethal doses per 0.02 ml) occurred in intracerebrally (i.c.) inoculated chicks on the second day post-infection. Complement-fixing antibody was detected on the 14th day post-inoculation in rabbits and on the 7th day in chickens. Infant rats less than 3 and 5 days of age died after subcutaneous (s.c.) and i.c. inoculation, respectively; older rats survived infection. Ife virus titres were highest in the brain following both i.c. and s.c. inoculation.

Prevalence of Ife virus infection in wild rodents and birds from Zaria, Nigeria.

One hundred eighty-three wild rodents and 38 wild birds trapped near Zaria were screened for virus and complement fixing (CF) antibody to Ife virus. Virus was not isolated but CF antibody was detected in 8% Cricetomys gambianus and 31% Arvicanthis niloticus tested. The presence of Ife virus has been documented now in three ecological zones of Nigeria.

Pathogenicity of Ife virus for Swiss albino mice.

Pathogenicity of Ife virus was studied in Swiss albino mice following four inoculation routes. Mice of all ages survived oral infection without seroconversion; subcutaneous (i.c.) and intraperitoneal (i.p.) infections lead to low titre antibody production. Only suckling mice (1-5 days old) succumbed to intracerebral (i.c.) inoculation with infectivity titres which decreased by age and average survival time (AST) increasing with age. Following i.c. inoculation to suckling mice, the brain infectivity titres increased progressively by days post-infection (p.i.). Virus was not recovered from the lungs and kidney but in low titre it was obtained from the liver, spleen, heart and blood at different days p.i. All organs examined showed evidence of complement fixing and immunofluorescent Ife virus antigen. No gross lesions were observed. The histopathological lesions were limited to the brain.

The Hitchner B1 strain of Newcastle disease virus induces high levels of IgA, IgG and IgM in newly hatched chicks.

Reaseheath line C chicks produced IgA, IgG and IgM in their serum, tears, spleen and Harderian gland (HG) as a consequence of oculotopical vaccination with the Hitchner B1 strain of Newcastle disease virus. The IgM response was seen first, at 5 days after vaccination, and antiviral IgM levels in the tears and serum were negatively correlated to the level of virus in HG over days 4 to 10 postinfection. The frequency of virus-specific IgM-antibody forming cells in the HG of 10-day-old birds that had been vaccinated at 1 day old could reach 1/30th of the total lymphoid cells prepared from the HG. Young chicks made an irregular or low response to inactivated virus by the intravenous route whereas 40-day-old birds made a high serum response to both live and inactivated virus. This emphasizes how day-old chicks respond well to live virus vaccination and that their IgM response is likely to have a role in the clearance of virus.

A serological survey for Rift Valley fever antibody in food animals in Kaduna and Sokoto States of Nigeria.

A total of 1106 serum samples from cattle, sheep, goats and camels were collected from Kaduna and Sokoto States of Nigeria. These were tested for the presence of antibody to Rift Valley fever virus by the agar gel immunodiffusion method. The antibody prevalence rates were 2.85% in cattle, 6.67% in sheep, 0.98% in goats and 3.13% in camels.

Serological evidence of Ife virus infection in Nigerian indigenous domestic ruminants.

Serological evidence of Ife virus infection was observed in cattle, sheep, goats and camels in both ecological zones of Sokoto and Kaduna States of Nigeria. The antibody prevalence rates differed between species and between zones, being highest in the guinea savanna. This is the first report of possible Ife virus infection in domestic ruminants.

Complement fixing antibodies to Orungo virus in food animals of Northern Nigeria.

In 1981 serum samples were collected from 1106 domestic ruminants in seven different locations in Kaduna and Sokoto States of Northern Nigeria. These states represent the part of the country where there has been no reports of clinical disease or antibody to Orungo virus. Orungo virus antibodies were detected in 26.7% of the sheep, 6.8% of the cattle, 30.7% of the goats and 37.5% of the camels tested by the complement fixation method. The antibody titer in the various positive samples were also determined. Hitherto, Orungo virus infection has not been reported in goats and camels in this country.