Molecular epidemiological study of canine rabies in the Free State province (South Africa) and Lesotho

There are two rabies virus biotypes recognized in southern Africa namely; the canid and mongoose rabies virus biotypes. The host vectors of canid rabies biotype in South Africa are domestic dogs, black-backed jackals and bat-eared foxes, whereas the mongoose rabies biotype is maintained by the yellow mongoose. The canid rabies virus was introduced into southern Africa from Angola (1940s) and spread within the subcontinent, firmly establishing itself in the domestic dog population in Zimbabwe (1950s) and South Africa (1960s). Canine rabies became established in the coastal regions of South Africa (KwaZulu Natal) in 1976 where it has been problematic ever since. Historical data demonstrate that canine rabies has spread from KwaZulu Natal into the north-eastern corner of Lesotho in 1982, spreading throughout the country and reaching the western border of Lesotho and South Africa (FS province) in the mid-1980s without penetrating into this region of South Africa. In contrast, the historical evidence suggests that mongoose rabies virus existed in southern Africa in the early 1800s. Mongoose rabies was confirmed in 1928 in South Africa and since then was consistently diagnosed in the yellow mongoose with apparent spill over into domestic animals on the central plateau of South Africa. The FS province was mainly associated with mongoose rabies; however, recent studies utilizing antigenic characterization have suggested an increase of the canid rabies biotype of RABV since the late 1990s, peaking in 2002. The aim of this investigation was to better understand the molecular epidemiology of canine rabies in the FS province by establishing genetic relationships between rabies viruses obtained from FS province and Lesotho, with the purpose of determining the origin of canine rabies into the province and the radiation of mongoose rabies biotype of RABV into dog host. The coding region of cytoplasmic domain of glycoprotein gene and G-L intergenic region of 113 rabies viruses from FS province and Lesotho was amplified and sequenced. It was found that canid rabies virus isolates from the FS province and those from Lesotho were very closely related demonstrating a mean nucleotide sequence homology of 99%. This result indicated a single overlapping epidemiological rabies cycle between the two regions. The results also confirmed that the spill over of mongoose rabies virus into dog host does not establish dog to dog transmission and therefore leads to dead end infection. Therefore parenteral vaccination of domestic dogs and cats remains an important priority in any effort to control rabies in these regions.Dissertation (MSc)--University of Pretoria, 2011.Microbiology and Plant Pathologyunrestricte

Antigenic characterisation of lyssaviruses in South Africa

There are at least six Lyssavirus species that have been isolated in Africa, which include classical rabies virus, Lagos bat virus, Mokola virus, Duvenhage virus, Shimoni bat virus and Ikoma lyssavirus. In this retrospective study, an analysis of the antigenic reactivity patterns of lyssaviruses in South Africa against a panel of 15 anti-nucleoprotein monoclonal antibodies was undertaken. A total of 624 brain specimens, collected between 2005 and 2009, confirmed as containing lyssavirus antigen by direct fluorescent antibody test, were subjected to antigenic differentiation. The lyssaviruses were differentiated into two species, namely rabies virus (99.5%) and Mokola virus (0.5%). Furthermore, rabies virus was further delineated into two common rabies biotypes in South Africa: canid and mongoose. Initially, it was found that the canid rabies biotype had two reactivity patterns; differential staining was observed with just one monoclonal antibody. This difference was likely to have been an artefact related to sample quality, as passage in cell culture restored staining. Mongoose rabies viruses were more heterogeneous, with seven antigenic reactivity patterns detected. Although Mokola viruses were identified in this study, prevalence and reservoir host species are yet to be established. These data demonstrate the usefulness of monoclonal antibody typing panels in lyssavirus surveillance with reference to emergence of new species or spread of rabies biotypes to new geographic zones.This work was partly funded by the Rabies Diagnostic Project, Onderstepoort Veterinary Research Institute (OVI 15/4/P001) and the European Virus Archive (EVA) (04/17/C215).http://www.ojvr.orgam201

Molecular detection of rabies lyssaviruses from dogs in Southeastern Nigeria : evidence of transboundary transmission of rabies in West Africa

Despite being the first country to register confirmed cases of Mokola and Lagos bat lyssaviruses (two very distant lyssaviruses), knowledge gaps, particularly on the molecular epidemiology of lyssaviruses, still exist in Nigeria. A total of 278 specimens were collected from dogs in southeastern Nigeria between October 2015 and July 2016, and 23 (8.3%) of these tested positive for lyssaviruses with the direct fluorescent antibody test (DFA). The lyssaviruses were genetically characterized by amplifying the highly conserved nucleoprotein (N) gene of the rabies lyssaviruses (RABVs) of the viral genome. Phylogenetic analyses of the nucleotide sequences showed that all the RABV sequences in this study were of the Africa-2 lineage. Our results demonstrated that transboundary transmission of rabies lyssavirus is a key event, given that one of the RABV sequences (MN196576) clustered with rabies variants from neighboring Niger Republic. Furthermore, three RABVs from dogs from Anambra State clustered separately forming a novel and distinct group. Our results demonstrated that transboundary transmission of RABLVs is a key driver in the spread of rabies in West Africa. In order for the successful control of this zoonotic disease, a multinational stepwise surveillance and elimination of rabies in Africa by 2030 is probably the solution for regional elimination.The Tertiary Educational Trust Fund (TETFund) of the Nigerian government through University of Nigeria IBR and Bench Space Intervention (TETFUND/DESS/UNI/NSUKKA/RP/VOL.V) and also the ARC-OVI National Assets [P10000029] Onderstepoort Veterinary Institute, South Africa.http://www.mdpi.com/journal/virusesam2021Veterinary Tropical Disease

Sero-Surveillance of Lyssavirus Specific Antibodies in Nigerian Fruit Bats (Eidolon helvum)

The aetiological agent of rabies is a member of the Lyssavirus genus (Rhabdoviridae family, order Mononegavirales). The disease (rabies) is endemic in many parts of Asia and Africa and still remains an important public and veterinary health threat. In Nigeria, there is a dearth of information on the natural infection and/or exposure of bat species to lyssaviruses. Therefore, this study was undertaken to assess the prevalence of rabies virus (RABV) neutralizing antibodies in sera obtained from bats from the central Plateau and North-East Bauchi States in Nigeria. Two hundred serum samples were collected from Nigerian fruit bats from six different locations and tested for anti-RABV antibodies using a commercial blocking ELISA. Of the 200 bat serum samples collected, one batch consisting of 111 samples did not meet the validation criteria and hence was not included in the final analysis. Of the remaining 89, only three (3.4%) contained anti-lyssavirus antibodies, demonstrating a low prevalence of lyssavirus antibodies in the study population. In order to further understand the exposure of bat species to phylogroup II lyssaviruses (Lagos bat virus and Mokola virus), the same panel of samples will be tested for neutralizing antibodies to phylogroup II members, viruses that do not cross-neutralize with members of phylogroup I

Detection of lyssavirus antigen and antibody levels among apparently healthy and suspected rabid dogs in South‑Eastern Nigeria

OBJECTIVES : Domestic dogs are the main reservoir of rabies virus (RABV) infection in Nigeria, thus surveillance of rabies in dog populations is crucial in order to understand the patterns of spread of infection and ultimately devise an appropriate rabies control strategy. This study determined the presence of lyssavirus antigen in brain tissues and anti-rabies antibodies in sera of apparently healthy and suspected-rabid dogs slaughtered for human consumption at local markets in South-Eastern Nigeria. RESULTS : Our findings demonstrated that 8.3% (n = 23) of brain tissues were lyssavirus positive and 2.5% (n = 25) of sera had rabies antibody levels as percentage blocking of 70% and above correlating with a cut-off value ≥ 0.5 IU/ mL in the fluorescent antibody neutralization test. There was an inverse correlation between lyssavirus positivity and rabies antibody levels confirming that infected individuals most often do not develop virus neutralizing antibodies to the disease. The low percentage of rabies antibodies in this dog population suggests a susceptible population at high risk to RABV infection. These findings highlight a huge challenge to national rabies programs and subsequent elimination of the disease from Nigeria, considering that majority of dogs are confined to rural communal areas, where parenteral dog vaccination is not routinely undertaken.Additional file 1. Geographical location of South Eastern Nigeria and the States involved in the study. Map of the study area.The authors thank staff of National Veterinary Research Institute, Vom Plateau State, Nigeria and OIE Rabies Reference Laboratory, Onderstepoort, South Africa for laboratory and technical support. We also thank Dr. Ekene Ezenduka for assistance with the data analysis.This work was partly funded by the Tertiary Educational Trust Fund (TETFund) of the Nigerian government through University of Nigeria IBR Intervention (TETFUND/DESS/UNI/NSUKKA/RP/VOL.V) and the ARC-OVI National Assets [P10000029]. The bench work was undertaken at the Rabies Unit, Onderstepoort Veterinary Institute, South Africa. The TETFund and ARC-OVI National Assets were involved in the design of the study, TETFund funded the collection of data and analyses in Nigeria, while the ARC-OVI was responsible for the analyses of data in South Africa and manuscript writing.https://bmcresnotes.biomedcentral.comam2019Veterinary Tropical Disease

Complete coding sequences of 23 South African domestic and wildlife rabies viruses

South African rabies viruses originating from dogs and jackals (canid viruses) are closely related and highlight cross-species transmission events between the two canine species. Rabies due to the canid lyssavirus variant is a significant public health matter in this country. The complete coding sequences of 23 canid lyssaviruses from South Africa are reported here.The National Research Foundation (NRF) of South Africa, ARC and the EU Framework Horizon 2020 Innovation Grant, European Virus Archive (EVAg).https://mra.asm.orgam2021Veterinary Tropical Disease