Doctoral Degrees (Medical Virology)

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Browsing Doctoral Degrees (Medical Virology) by Author "Kleinhans, Bronwyn"

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    Identification and characterisation of paramyxoviruses in species-rich small mammals from South Africa
    (Stellenbosch : Stellenbosch University, 2022-12) Kleinhans, Bronwyn; Preiser, Wolfgang; Ithete, Ndapewa Laudika; Drexler, Jan Felix; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology. Medical Virology.
    ENGLISH ABSTRACT: Paramyxoviruses are negative-sense RNA viruses and include a substantial collection of ubiquitous viruses, comprising one of the most important viral groups with numerous pathogens historically impacting on public and veterinary health. The Paramyxoviridae family consists of four subfamilies including Avulavirinae (genera: Metaavulavirus, Orthoavulavirus and Paraavulavirus), Metaparamyxovirinae (genus: Synodonvirus), Orthoparamyxovirinae (genera: Aquaparamyxovirus, Ferlavirus, Henipavirus, Jeilongvirus, Morbillivirus, Narmovirus, Respirovirus and Salemvirus) and Rubulavirinae (genera: Orthorubulavirus and Pararubulavirus). Over the past three decades, an increasing number of novel paramyxoviruses of especially the Orthoparamyxovirinae and Rubulavirinae subfamilies have emerged from small mammal reservoir hosts, some of which, especially the deadly henipaviruses, Hendra- and Nipah virus, have demonstrated a propensity to spillover from their natural reservoir hosts into human and domestic animal populations. Although some small mammals have been implicated as potential hosts for novel paramyxoviruses within southern Africa, little to no data exists on such discovery in insectivorous bats, rodents and particularly shrews and sengis in South Africa. This study identified an additional 23 previously unimplicated species representing four different orders (Chiroptera, Eulipotyphla, Macroscelidea and Rodentia), greatly expanding on the known host and geographic range of these putative paramyxoviruses, reiterating this group of virus’ ubiquitous nature and high diversity. The presumptive paramyxoviruses discovered in this study demonstrated phylogenetic relatedness to at least five of the known genera including: Henipavirus, Jeilongvirus, Morbillivirus, Narmovirus and Rubulavirus as well as to previously discovered viral sequences clustering within the Orthoparamyxovirinae subfamily but that could not be assigned to any of the currently known genera. Unique to this study and of particular value in the South African context was the discovery that: Cape horseshoe bats (Rhinolophus capensis) harbour different variants / strains of a paramyxovirus displaying multiple nonsynonymous mutations resulting in amino acid changes, raising concerns over these putative paramyxoviruses’ zoonotic potential; the widely distributed and populous Rhabdomys (R. bechuanae, R. dilectus, R. intermedius and R. pumilio), endemic to southern Africa, harbour diverse and abundant (overall prevalence of 19.41% [106/546]) paramyxoviruses, displaying diversity on the individual, species and population levels; at least four different shrew species commonly found in South Africa were implicated as hosts for putative henipaviruses; the sustained presence of one of these novel viruses in greater red musk shrews (Crocidura flavescens) implicated this particular species as the reservoir host thereof, of which the near full-length genome sequence further revealed a close phylogenetic relationship to the rat-borne henipavirus, Mòjiāng virus. Given the abundance and diversity of novel potential paramyxoviruses discovered herein and the implication of a multitude of previously unimplicated species as potential reservoir hosts, this study reaffirms the importance and need for ongoing surveillance efforts of especially small mammals in South Africa. This study further highlights the importance of not only the identification of novel paramyxoviruses but also their characterisation, especially those demonstrating close relation to pathogenic members within the family. Further investigation into host-pathogen dynamics at the wildlife – domestic animal – human interface is however warranted to establish the potential for these viruses’ ability to spillover into humans and/or their domestic animals.