Biomedical subjects
Publications and source records attributed to A Fabiyi.
Orungo virus is relatively sensitive to lipid solvents and sodium deoxycholate. It is readily inactivated at 37 degrees C and above, by u.v. irradiation, BP and formalin. Orungo virus is ph 3.0 labile, but stable at ph range of 5.0-7.0. Multiplication of Orungo virus in BHK-21 cell cultures is not affected in the presence of 5-iododeoxyuridine.
Various sero-epidemiologic studies, including the preliminary report from Ibadan, have established that most women with premalignant and malignant carcinoma of the cervix have serologic evidence of infection of herpes type-2 virus. Using immunofluorescence method, the earlier report in Ibadan was confirmed, whereby the prevalence of HT-2 virus antibodies was shown to be significantly associated with carcinoma of the cervix, especially the squamous cell type. However, there was no such association with the grade and stage of the disease.
Numerous sero-epidemiologic studies have noted an association between Herpes Type 2 (HT-2) virus and carcinoma of the cervix. In a study to evaluate the role of this virus, if any, on the etiology of extra cervical pelvic malignancies in Ibadan, the prevalence of HT-2 virus antibodies was found not to be significantly different in patients with extra cervical pelvic malignancies (carcinoma of the vulva and malignant trophoblastic disease) and cases of chronic cervicitis when compared with healthy controls. It was therefore concluded that no association could be found between HT-2 virus and extra cervical pelvic malignancies.
Orungo virus was studied in cell culture and mice by light and electron microscopy. The virus developed in the cytoplasm of infected cells in mouse brain and cell culture in association with a specific viral granular matrix and accompanying filaments. Virus particle size was 63 nm with a core diameter of 34 nm. Most particles were released from infected cells by lysis, but some budded through membranes and assumed a "pseudoenvelope". In its morphology and mode of morphogenesis, Orungo virus was indistinguishable from other described orbiviruses.
Using two serological techniques, eight Nigerian West Nile virus isolates were investigated to determine antigenic relationships among them, and to find out if these virus isolates were related to West Nile virus strains from the different zoogeographic areas of the world. One virus differed significantly from the seven other strains and was later found to be a strain of Usutu virus. The remaining strains were differentiated into two serological intratypic groups depending on their cross reactions with two strains which served as prototypes for each group. Five virus isolates which constitute one of the antigenic groups were found to be related to the Egypt 101 strain of West Nile virus originating from general Palearctic zone (European and Middle East). The other two virus isolates did not show any relationship to the strains from any of the different zoogeographic zones.
The agar-gel diffusion (AGD) and the immunoelectrophoretic (IEP) techniques were employed in the differentiation of virus strains of the Bwamba-Pongola group. These techniques were found to be more specific than either the complement fixation (CF) or the neutralization (N) test in the differentiation of Bwamba and Pongola viurses. Of 22 virus strains isolated in Nigeria and previously typed as strains of Bwamba virus by CF and N tests, 12 strains of mosquito origin were definitely classified as Pongola viruses and 10 of human origin as Bwamba viruses by the AGD and IEP techniques.
Sera from 180 blood donors in Sierra Leone were examined by combined hemagglutination - inhibition, complement fixation, and neutralization tests for antibodies against 10 arbovirus. The donors were 20 to 40 years old and resident at Panguma, Tongo, Serabu and Segbwema. Thirty sera (16.6%) had antibodies to group B viruses, the majority of which were to yellow fever virus as confirmed by N tests. Nineteen sera had antibodies to Arumowot virus and 4 to Sindbis virus. N antibodies against UgMP 359, a non-group B virus, were demonstrated in 12 of the sera. No antibodies were found against Bwamba and Ilesha viruses.
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Two "new" virus infections, Marburg and Lassa fever, now constitute diseases of public health importance in several countries of Africa, especially West Africa. Lassa fever has an insidious onset, is initially difficult to diagnose, has "nonspecific" clinical symptoms which have been confused with yellow fever and typhoid, shows evidence of persistent infection, is tremendously contagious, has a high mortality rate, and in particular exhibits unusual nosocomial propensity. It has also been shown to be the cause of premature births and spontaneous abortions in pregnant women. The virus is transmitted by the respiratory route and by direct contact with contaminated materials. Persistent complement-fixing antibodies have been demonstrated in patients recovered from the disease. The causative agent, a member of the arenavirus group, is known to be enzootic in rodents, especially Mastomys natalensis.
Various studies have associated Herpes Type-2 (HT-2) virus with carcinoma of the cervix, especially the squamous cell type. In the present study, prevalence of HT-2 virus antibodies was found to be significantly higher in patients with squamous cell carcinoma of the cervix than in cases with squamous cell carcinoma of sites other than the cervix, and other pelvic and extrapelvic malignancies (P less than 0.001). It was concluded that no association could be found between Herpes Type-2 virus and malignancies of sites other than the cervix.
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Exfoliated cells from the cervices of 22 patients with histologically diagnosed squamous cell carcinoma of the cervix and from those of 24 control women were examined for herpes subtype 2 (HT-2) antigens by indirect immunofluorescence studies. This method demonstrated that cells from all the patients with carcinoma contained antigens related to HT-2 virus. In contrast, squamous cells from the cervices of 24 control women with no cervical disease and of 2 women with chronic cervicitis did not contain such HT-2 antigens. Although an etiologic role of HT-2 virus infection cannot yet be established, it is probable that such infection precedes neoplastic changes.
Sera from humans, birds, domestic and wild animals, from 17 localities in four ecological zones of Nigeria were tested for neutralizing antibody to Orungo virus. A total of 1197 human sera were tested, of which 277 (23.1%) were positive for Rungo antibody. The highest prevalence (34.2%) was found in the northern Guinea Savannah zone. The prevalence in the other zones were 29.9% in the Southern Guinea Savannah, 24.3% in the Derived Savannah and 17.0% in the rainforest. Significant differences in antibody prevalence were found between, the wet forested area and the drier Savannah regions, with an increasing trend from the wetter to the drier zones. Over 50% of sheep, with about 24% of monkeys and 14% of cows tested were positive for Orungo virus N antibody. It is suggested that man and animals are involved in the transmission cycle of Orungo virus in Nigeria, possibly with Aedes spp. mosquitoes acting as an important vector.
Carcinoma of the cervix is by far the commonest gynecologic malignancy seen in Ibadan, Nigeria. In a study aimed at investigating the role of herpesvirus type 2 (HT-2) in its pathogenesis, antibodies to HT-2 were detected by immunofluorescence above a titer of 640 in 31 (70.5 percent) of 44 women with invasive carcinoma of the cervix as compared with five (11.1 percent) of 45 healthy women of the same age group. Analysis according to histologic types of growths showed that 31 (83.8 percent) of 37 cases of squamous-cell carcinoma had antibodies above a titer of 640, whereas none of the other types (one adenocarcinoma and six undifferentiated carcinoma of the cervix) had antibodies above this titer. It was concluded that the results of the present study support the hypothesis of an association between HT-2 and carcinoma of the cervix, most especially the squamous-cell type.
A survey to detect individuals with antibodies to Lassa virus was undertaken among hospital personnel in the eastern and southern provinces of Sierra Leone late in 1974. Sera were evaluated by the complement fixation test. The data obtained showed that some contacts of Lassa fever patients in the 1972 epidemic had developed antibodies to the virus; individuals who had never reported being sick also showed evidence of infection, with significant CF antibody titres in their sera. Surviving Lassa fever patients from the 1972 epidemic still had easily measurable levels of persisting CF antibodies. The significance of these data is discussed; in addition it is recommended that the CF test should continue to be the method of choice in mass surveys for this virus disease until other tests can be developed.
Rodents were trapped in the Benue-Plateau and North-Eastern States of Nigeria where Lassa fever had been reported in previous years. Eight Lassa virus strains were isolated from tissues and blood of rodents identified in the field as being of 3 different species: Mastomys natalensis, Rattus rattus, and Mus minutoides. All the infected rodents were collected in village habitats. These isolations indicate the presence of Lassa virus in wild rodents in Nigeria during periods when no human infections were evident.Prior studies in Sierra Leone have indicated that a single rodent species, M. natalensis, may be the important reservoir host of Lassa virus. Since the present study indicates that other rodent species may be involved as well, the ecology of Lassa virus may be more complicated than was heretofore supposed. In view of the importance of determining the geographic and species range of rodent hosts of Lassa virus, and because of the problems inherent in rodent identification under austere field conditions, it is urgent that further studies be conducted in the same areas of Nigeria to confirm these findings.
Three hundred and fifty-one persons were tested for HI antibody to arbovirus Groups A, B and Ingwavuma viruses in Ilesha and Oshogbo, two towns in western Nigeria. Chikungunya accouted for most Group A infections (39%). Antibodies to Group B virus were distributed as follows: Dengue 22%, Yellow Fever 25%, West Nile 28% and Wesselsbron 30%. Few sera 5% were positive to Ingwavuma. No virus was isolated from 188 blood specimens processed for virus isolation.
West African Dwarf sheep were challenged with a low mouse brain-passaged Rift Valley fever virus (Ib-AR 55172) isolated from Nigeria. Viraemia, mild febrile reaction and neutralising antibodies were demonstrated in inoculated animals.