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Completed research project

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Summary / Zusammenfassung Rabies, a disease caused by Lyssaviruses of the Rhabdovirus family is widespread on the African continent. The classical rabiesvirus (genotype 1) finds its main reservoir in the high number of unvaccinated, stray domestic dogs (Canis familiaris) [1]. In addition Jackals (Canis mesomelas and Canis adustus)[2], bat eared foxes (Otocyon megalotis)[3] and mongoose species (Herpestidae)[4] are believed to locally support rabies cycles independent of the domestic dog. From these abundant vector species rabies is frequently transmitted to other mammal species as rabies cases in cattle [5], in African wild dog (Lycaon pictus)[6] and in the Kudu antelope (Tragelaphus strepsiceros) [7] show. Also present in Africa are three types of lyssaviruses circulating in bats: Lagos Bat virus (genotype 2), Mokola virus (genotype 3) and Duvenhage virus (genotype 4). Despite the overwhelming evidence that rabies is prevalent among lion’s prey and food competitor species there are only a handful of reported rabies cases in lions to date. The highest number of cases to our knowledge was found in Namibia in 1980, where 4 lions were reported to have died of rabies [8]. We therefore hypothesise that lions are less susceptible to the disease and can acquire protective antibodies against the rabies virus from natural infection. To investigate this assumption we perform RFFIT (Rapid fluorescent focus inhibition test) on lion sera samples collected during previous studies [9, 10]. 154 lion sera samples originating from Serengeti National Park and the Ngorongoro Crater in Tanzania (N=88); the Central Kalahari Game Reserve and Khutse Game Reserve in Botswana (N=28); and from different locations in Zimbabwe (N=34) were chosen. To detect possible seroconversion 7 double specimen from animals sampled a second time after 2-4 years were included. Additionally 4 serum samples from lion cubs that were born in Basel Zoo are used as negative controls.
The RFFIT detects neutralizing antibodies directed against the glycoprotein of the rabies virus. However there are studies showing, that neutralizing antibodies against classical rabies virus fail to protect Lagos Bat and Mokola virus indicating that the lyssavirus family is divided into two groups between which no cross protection occurs [11]. Therefore we also perform a Western Blot and an ELISA test on the sera with an E. coli recombinant rabies nucleoprotein to detect antibodies against the nucleoprotein, which is more conserved within the lyssavirus group.
Although antibodies against rabies are believed to only appear in the terminal phase of the disease and therefore usually can’t prevent the fatal outcome of rabies, antibodies in non vaccinated animals are frequently detected in serosurveys. In spotted hyenas (Crocuta crocuta) a high antibody prevalence was shown, that may have resulted from constant low infection pressure by small viral loads, due to the hyenas special behaviour of licking one another’s muzzles as a greeting ceremony [12]. Should we indeed find significant antibody prevalence in lions, further investigations would have to show if this feline specie is protected through a similar epidemiological peculiarity as in the case of the hyena or if the immune system of lions has acquired a special strategy to fight rabies.
Publications / Publikationen 1. Cleaveland S, Hampson K, Kaare M: Living with rabies in Africa. Vet Rec 2007, 161(9):293-294.
2. Loveridge AJ, Macdonald DW: Seasonality in spatial organization and dispersal of sympatric jackals (Canis mesomelas and C. adustus): implications for rabies management. Journal of Zoology 2001, 253(01):101-111.
3. Sabeta CT, Mansfield KL, McElhinney LM, Fooks AR, Nel LH: Molecular epidemiology of rabies in bat-eared foxes (Otocyon megalotis) in South Africa. Virus Res 2007, 129(1):1-10.
4. Nel LH, Sabeta CT, Teichman Bv, Jaftha JB, Rupprecht CE, Bingham J: Mongoose rabies in southern Africa: a re-evaluation based on molecular epidemiology. Virus Research 2005, 109(2):165-173.
5. Moagabo KT, Monyame KB, Baipoledi EK, Letshwenyo M, Mapitse N, Hyera JMK: A retrospective longitudinal study of animal and human rabies in Botswana 1989-2006, vol. 76; 2010.
6. Gascoyne SC, King AA, Laurenson MK, Borner M, Schildger B, Barrat J: Aspects of rabies infection and control in the conservation of the African wild dog (Lycaon pictus) in the Serengeti region, Tanzania. Onderstepoort J Vet Res 1993, 60(4):415-420.
7. Mansfield K, McElhinney L, Hubschle O, Mettler F, Sabeta C, Nel LH, Fooks AR: A molecular epidemiological study of rabies epizootics in kudu (Tragelaphus strepsiceros) in Namibia. BMC Vet Res 2006, 2:2.
8. Swanepoel R, Barnard BJ, Meredith CD, Bishop GC, Bruckner GK, Foggin CM, Hubschle OJ: Rabies in southern Africa. Onderstepoort J Vet Res 1993, 60(4):325-346.
9. Hofmann-Lehmann R, Fehr D, Grob M, Elgizoli M, Packer C, Martenson JS, O'Brien SJ, Lutz H: Prevalence of antibodies to feline parvovirus, calicivirus, herpesvirus, coronavirus, and immunodeficiency virus and of feline leukemia virus antigen and the interrelationship of these viral infections in free-ranging lions in east Africa. Clin Diagn Lab Immunol 1996, 3(5):554-562.
10. Ramsauer S, Bay G, Meli M, Hofmann-Lehmann R, Lutz H: Seroprevalence of selected infectious agents in a free-ranging, low-density lion population in the Central Kalahari Game Reserves in Botswana. Clin Vaccine Immunol 2007, 14(6):808-810.
11. Bahloul C, Jacob Y, Tordo N, Perrin P: DNA-based immunization for exploring the enlargement of immunological cross-reactivity against the lyssaviruses. Vaccine 1998, 16(4):417-425.
12. East ML, Hofer H, Cox JH, Wulle U, Wiik H, Pitra C: Regular exposure to rabies virus and lack of symptomatic disease in Serengeti spotted hyenas. Proc Natl Acad Sci U S A 2001, 98(26):15026-15031.
Keywords / Suchbegriffe Rabies, serosurvey, panthera leo
Project leadership and contacts /
Projektleitung und Kontakte
Prof. Dr. Hans Lutz (Project Leader)
Dr. Marina Meli
Med. vet Monique Léchenne
Funding source(s) /
Unterstützt durch
No project-specific funding
In collaboration with /
In Zusammenarbeit mit
Dr. H. Bourhy
Unité Dynamique des lyssavirus et adaptation à l'hôte - CNR Rage
Institut Pasteur
25 Rue du Docteur Roux
75015 Paris
Duration of Project / Projektdauer Sep 2010 to Mar 2011