This paper reports the isolation and identification of Ukauwa virus, an agent closely related to the prototype Bunyamwera virus, from the serum of a Nigerian adult male suffering from a mild febrile illness.
ISOLATION OF THE VIRUS:
On the evening of January 13th, 1960, an adult male Nigerian of the Ibo tribe was seen at Yaba, Lagos, complaining of headache, pains in the joint, malaise and fever which had begun the previous evening. His temperature was 100°F. and there were no abnormal signs on physical examination. These symptoms subsided within a week, although the patient complained of abdominal pain during the last 2 or 3 days of illness. A sample of blood was collected when the patient was first seen, an undiluted serum was used to inoculate groups of 3-day-old mice by the intracerebral and intraperitoneal routes. There were no deaths at 16 and 40 hours after inoculation, but by 60 hours all but three of the infant mice were found dead. The three surviving sick mice were killed, one brain was fixed for histological examination, another was stored at - 50°C. and a third was homogenized in 0.75 per cent bovine plasma albumin for further passage in infant mice. Bacteriological culture media inoculated with infected mouse brain suspensions remained sterile and the agent was found to pass through a Seitz EK filter pad. When tenfold dilutions of the original acute phase human serum which had been stored at - 50°C. for about 2 weeks were inoculated into infant mice deaths again followed after an Incubation period of about 60 hours, the infectivity titre of the specimen being 10-2.75 (aproximately 600 LD 50 per 0.01 ml. of serum). A second blood sample was collected 3 weeks after the initial illnes Mouse protection tests carried out on the acute and convalescent sera showed that the acute phase sample failed to neutralize the virus which had been isolated from this material, whereas the convalescent serum sample neutralized more than 100 LD 50 of virus. Concurrent tests on the sera of 15 Europeans and Africans, living in the Lagos area, and complaining of similar symptoms, failed to show the presence of antibodies to this virus.