Immunology of bats and their viruses: challenges and opportunities

Abstract

Bats are reservoir hosts of several high-impact viruses that cause significant human diseases, including Nipah virus, Marburg virus and rabies virus. They also harbor many other viruses that are thought to have caused disease in humans after spillover into intermediate hosts, including SARS and MERS coronaviruses. As is usual with reservoir hosts, these viruses apparently cause little or no pathology in bats. Despite the importance of bats as reservoir hosts of zoonotic and potentially zoonotic agents, virtually nothing is known about the host/virus relationships; principally because few colonies of bats are available for experimental infections, a lack of reagents, methods and expertise for studying bat antiviral responses and immunology, and the difficulty of conducting meaningful field work. These challenges can be addressed, in part, with new technologies that are species-independent that can provide insight into the interactions of bats and viruses, which should clarify how the viruses persist in nature, and what risk factors might facilitate transmission to humans and livestock.

Figure 1

Bat husbandry and manipulations. Establishment of bat colonies for experimental research requires enrichment for successful maintenance and reproduction. (A) Landscape fabric attached to walls provides roosting substrate; (B) Hanging of fruit on skewers can provide enrichment for frugivorous bats by stimulating foraging behavior. A wing band (green) is present with a unique identification number; (C, D) Hanging of inverted wicker or metal baskets provide additional roosting substrates; (E) A female Seba’s fruit-eating bat (Carollia perspicillata) with offspring; (F) Blood collection from a bat wing; (G) Oral swab for virus collection. Photos are by the author and are of the colony at the University of Northern Colorado [3,66,106].

Figure 2

Reactome mapping of differentially-expressed genes. Abundance of differentially-expressed IFNγ pathway transcripts in Pirital arenavirus-infected hamster livers relative to uninfected group were estimated by RSEM and statistically analyzed with DESeq. The symbols for the elevated genes were imported into the Reactome plugin of Cytoscape for pathway analysis. Genes in purple boxes were elevated in infected animals (author’s unpublished data) and suggests this pathway is important in the host response to the virus.

Figure 3

Amino acid alignment of mature GM-CSF from horse, P. alecto and M. lucifugus. Identical amino acids in dark gray, similar amino acids in light gray, and dissimilar amino acids in white, consensus below. The red box is the putative helix A involved in binding to the GM-CSF receptor. Alignment performed with MacVector using the default CLUSTAW settings [128].