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Biomedical subjects

O Tomori

Publications and source records attributed to O Tomori.

At least 37 records · Page 2Linked to original sources
PubMed1990

Detection of Mokola virus neutralising antibodies in Nigerian dogs.

Five hundred healthy Nigerian dogs were randomly selected and bled for serological detection of antibodies to lyssa-viruses, including Mokola, Lagos bat and Duvenhage viruses. The canine sera were screened for virus neutralising antibodies by a modification of the rapid fluorescent focus inhibition technique. Three serum samples were seropositive to Mokola virus but all were negative to Lagos bat and Duvenhage viruses. The three seropositive Mokola samples were also negative for rabies virus neutralising antibodies. This finding may explain occasional rabies-like canine mortalities within one year of antirabies vaccination in Nigeria.

Animals↗
PubMed1989

Inactivated oil emulsion vaccines from selected clones of Newcastle disease virus.

The immunogenicity of oil emulsion (OE) vaccines prepared from two selected clones of a Nigerian strain of Newcastle disease virus and two commercial vaccine strains were compared. Geometric mean haemagglutination inhibition titre was lowest in OE-Lasota, although all four vaccines gave 100% protection against clinical Newcastle disease. The use of OE vaccines is recommended for commercial use in Nigeria.

Animals↗
PubMed1988

Viral hemorrhagic fever antibodies in Nigerian populations.

Using the immunofluorescence test, a serosurvey for antibodies to five viral agents associated with hemorrhagic febrile infections was conducted with 1,677 human sera from different parts of Nigeria. Three hundred fifty-seven (21.3%) were positive for Lassa virus antibody, while antibodies to Rift Valley fever virus were detected in 42 (2.5%) of the sera. Testing for Rift Valley fever virus antibody was confirmed by plaque reduction neutralization test. Antibodies to Ebola and Marburg viruses were detected in 30 and 29 sera, respectively. Of the 357 Lassa virus antibody-positive sera, 297 (83.2%) were positive for Lassa only. In contrast, sera positive for Marburg were positive in combination with Lassa, Ebola, or Rift Valley fever viruses. Antibodies to Lassa and Rift Valley fever viruses were found in all locations in Nigeria, whereas Ebola and Marburg antibodies were found mainly in the northern savanna zones of Benue and Gongola, but not in the rain forest area of Ondo.

Adolescent↗
PubMed1987

Standardization of a plaque assay for Lassa virus.

The plaque reduction neutralization test (PRNT) has been used routinely in serological studies with such arenaviruses as Junin, Machupo, and Parana. However, difficulties have been encountered in using the PRNT for LCM virus, while conflicting views have been expressed about the reliability and efficacy of the test with Lassa virus. We have therefore investigated and evaluated the plaque assay for Lassa virus. In addition, the suitability of the PRNT for determining the potency of a serum and its efficacy in passive immunization for the treatment of Lassa fever was also investigated. The Lassa virus plaque assay satisfied the criteria proposed by Cooper [1961] for determining satisfactory plaque technique. Lassa virus plaques appear within 3 days of inoculating Vero cell cultures. By day 5, the plaques are clearly defined, discrete, and measure 1.5 to 2.0 mm. In the plaque reduction neutralization test, the use of native non-inactivated serum was required for a reliable and reproducible determination of serum antibody titer. The potency and suitability of a serum for Lassa fever serotherapy was determined by the use of a constant serum-varying virus (CS-VV) and/or a constant virus-varying serum (CV-VS) PRN technique.

Animals↗
PubMed1987

Differentiation between two African arenaviruses (Lassa and Mozambique) by plaque assay.

The biological characteristics of Lassa and Mozambique viruses were compared by plaque assay. Both viruses produced plaques under the same conditions, however, Lassa virus plaques measured on average 2 mm in diameter being twice as large as the Mozambique virus plaques. By plaque reduction tests, cross protection was demonstrated between both viruses showing that Lassa and Mozambique viruses are distinct but related.

Animals↗
PubMed1981

Recovery of a Lassa-related arenavirus in Zimbabwe.

Immunofluorescent antibodies to "Mozambique" virus, a close relative of Lassa virus, were found in 11 of 55 Mastomys natalensis and 1 of 13 Aethomys chrysophilus rodents captured near Que Que and Chiredzi, Zimbabwe. Six strains of Mozambique virus, identified by use of specific monoclonal antibodies to the agent, were recovered from visceral tissues of M. natalensis rodents. All Mastomys having virus or antibodies to this agent were of the chromosomal form 2N = 32 (M. natalensis). These data extend the area of geographic occurrence of this virus, which was initially recognized in Mozambique and which may represent a naturally attenuated antigenic variant of human pathogenic West African Lassa virus.

Animals↗
PubMed1981

Arbovirus infections among laboratory personnel in Ibadan, Nigeria.

Laboratory-acquired infections encountered between 1963 and 1977 among personnel of the Virus Research Laboratory, Ibadan, Nigeria, are reported. Two cases of chikungunya infection occurred and one each with Dugbe, Wesselsbron, and dengue viruses. In each case, virus was isolated or development of antibody demonstrated. Among virus and two each to chikungunya and Rift Valley fever viruses, without experiencing any clinically recognized disease.

Adult↗
PubMed1980

Monoclonal antibodies to lymphocytic choriomeningitis virus react with pathogenic arenaviruses.

Certain arenaviruses have become widely recognized as important human pathogens, the most notable among these being Lassa virus, the causative agent of Lassa fever. Two other members of the group, Junin and Machupo virus, are the aetiological agents of Argentine and Bolivian haemorrhagic fevers, respectively. All these agents share both morphological features and to varying degrees serological cross-reactivity with other non-pathogenic arenaviruses. Despite the evident clinical importance of these viruses, work to define their physiochemical structure and to develop rapid and precise diagnostic techniques has been slow. Consequently, the definitive relationships among West African Lassa strains, strains of a related agent from Mozambique and of an Old World arenavirus, lymphocytic choriomeningitis (LCM), have not been established. This problem is of more than simple taxonomic importance in view of the fact that a Mozambique virus strain produced subclinical infection in experimental monkeys which were then resistant to challenge with monkey and human virulent Lassa virus from Sierra Leone. We have explored the use of monoclonal hybridoma antibodies generated against relatively less hazardous arenaviruses to define antigens cross-reactive with the important human pathogens of the group. Here we describe the use of monoclonal antibodies directed against LCM, virus to define antigenic specificities shared among LCM, Lassa and Mozambique viruses.

Antibodies, Viral↗
PubMed1980

Wild life rabies in Nigeria: experimental infection and transmission studies with the shrew (Crocidura sp.).

Wild caught shrews were infected with rabies virus strains by the intramuscular, subcutaneous and oral routes. Inoculated animals became sick within four to seven days of inoculation with characteristic dumb rabies symptomatology. The significant symptom was a progressive loss of aggressiveness and an unbalanced gait. The course of illness was 36-48 hours. Transmission of rabies virus to susceptible laboratory mice was successful only with shrews which had been infected orally and allowed to bite adult mice soon after infection. This suggests a mechanical role in the transmission of rabies. Virus was isolated only from shrews infected with street or wild strains of rabies, but not with vaccine or fixed rabies strains.

Animals↗
PubMed1980

Effect of storage temperature on the stability of Lassa virus complement-fixing antigen.

Inactivated Lassa virus complement-fixing antigen is normally prepared as a wet frozen antigen, and shipped in dry ice from the Center for Disease Control, Atlanta, Georgia, USA, to other laboratories not equipped for handling live Lassa virus. However, with this antigen there is a considerable loss of potency during shipping. In the search for a more stable antigen, inactivated Lassa antigen was lyophilized and subjected to different storage temperatures. Lyophilization did not significantly affect the CF titre, and the lyophilized antigen remained stable for 15 and 28 days at 25 degrees C and 4 degrees C, respectively.

Animals↗
PubMed1979

Clinical, virological and serological response of the West African dwarf sheep to experimental infection with different strains of Rift Valley fever virus.

West African dwarf sheep were inoculated with three different strains of Rift Valley fever virus (RVFV). Using infective mouse serum as the source of virus classical RVFV disease characterised by sudden onset, a sharp but transient febrile response, viraemia, abortions and the development of specific RVFV antibodies in surviving animals was observed. The severity of clinical response was, however, dependent on the strain of virus used, with animals inoculated with Smithburn's neuroadapted strain showing a milder response than those inoculated with either the Nigerian or Lunyo strain. The inoculation of sheep with RVFV infective mouse brain material of the three different strains resulted in a mild febrile response with low level viraemia. Immune sera from sheep inoculated with both the Nigerian and Smithburn's neurotropic strains did not neutralise the Lunyo virus strain in a mouse intracerebral neutralisation test; the reverse, however, was not the case. The findings indicate that the West African dwarf sheep is highly susceptible to RVFV infection and that previous reports of only a mild clinical response following inoculation with the Nigerian strain were due to infective mouse brain rather than infective mouse serum.

Animals↗
PubMed1979

Immunological reactions of Rift Valley fever virus strains from East and West Africa.

Three strains of Rift Valley fever virus, namely Nigerian (NIG), Smithburn's neurotropic (SNT), and Lunyo variant (LUN) were compared by complement fixation (CF), neutralisation (N), haemagglutination/haemagglutination-inhibition (HA/HI) and agar gel diffusion (AGD) tests. They showed reciprocal cross-reactivity in CF tests. In N tests, using immune sheep sera, there was reciprocal cross-neutralisation between the NIG and SNT strains, but not with the LUN strain, the antiserum of which neutralised both NIG and SNT antigens whereas the reverse was not the case. When hyperimmune mouse ascitic fluid was employed in N tests, there was cross-reactivity between the three strains. Both the NIG and SNT strains yielded haemagglutinins, but not the LUN strain. Furthermore, by the antibody absorption and AGD techniques, the NIG and SNT strains were found to be identical and distinct from the LUN variant strain. The techniques found most useful in distinguishing between the three strains were HA and AGD. Laboratory neuro-adaptation of the classical pantropic virus did not appear to affect its haemagglutination activity.

Animals↗