Studies on the prevalence of viral pathogens in bat species inhabiting Wavul Galge cave, Sri Lanka

Abstract

Bats of the order Chiroptera are globally distributed mammals and known to be the reservoir of numerous human pathogenic viruses. The increasing emergence of infectious disease outbreaks in the past century has also enhanced the research on bats and their associated viruses. The underlying project of this thesis also aims to assess the prevalence of viruses in Sri Lanka and their possible impact on public health issues. The focus of this thesis was the virological study of bats inhabiting Wavul Galge cave (Koslanda, Sri Lanka). The bats of the species Miniopterus fuliginosus, Rousettus leschenaultii,Rhinolophus rouxii, Hipposideros speoris and Hipposideros lankadiva live in one of the largest sympatric colonies that are known in Sri Lanka. Three major aims were pursued in this work. First, three bat sampling sessions were conducted in Wavul Galge to collect different sample types from all bat species. In this context, the bat sampling was optimized for future studies to do structured and reasonable samplings by considering virological, microbial, zoological, ecological and further aspects. Second, a variety of molecular virus detection methods was applied to estimate the prevalence of different viruses in the collected bat samples. Coronaviruses and Paramyxoviruses were identified in the bat species M. fuliginosus and R. leschenaultii. Furthermore, a full genome sequence of an α-Coronavirus derived from M. fuliginosus was assembled from NGS data. Also, a virome analysis of M. fuliginosus bats was obtained from mNGS data revealing the presence of further viruses. With this, viral sequences related to Astroviridae, Coronaviridae, Iflaviridae, Paramyxoviridae, Picornaviridae and unclassified Riboviria were detected. Third, the obtained data were further used for in-depth sequence analysis, phylogenetic reconstruction and evaluation of the human pathogenic potential. Based on the available data, this human pathogenic potential was assessed to be rather low in all novel virus strains. Summarized, the presented results of this thesis represent the first evidence of different viruses in cave-dwelling bat species from Sri Lanka. Further bat studies in this cave and other locations will increase the knowledge of virus prevalence in different bat species from Sri Lanka.