Time of year, age class and body condition predict Hendra virus infection in Australian black flying foxes (Pteropus alecto)

Abstract

Hendra virus (HeV) continues to cause fatal infection in horses and threaten infection in close-contact humans in eastern Australia. Species of Pteropus bats (flying-foxes) are the natural reservoir of the virus. We caught and sampled flying-foxes from a multispecies roost in southeast Queensland, Australia on eight occasions between June 2013 and June 2014. The effects of sample date, species, sex, age class, body condition score (BCS), pregnancy and lactation on HeV antibody prevalence, log-transformed median fluorescent intensity (lnMFI) values and HeV RNA status were assessed using unbalanced generalised linear models. A total of 1968 flying-foxes were sampled, comprising 1012 Pteropus alecto, 742 P. poliocephalus and 214 P. scapulatus. Sample date, species and age class were each statistically associated with HeV RNA status, antibody status and lnMFI values; BCS was statistically associated with HeV RNA status and antibody status. The findings support immunologically naïve sub-adult P. alecto playing an important role in maintaining HeV infection at a population level. The biological significance of the association between BCS and HeV RNA status, and BCS and HeV antibody status, is less clear and warrants further investigation. Contrary to previous studies, we found no direct association between HeV infection and pregnancy or lactation. The findings in P. poliocephalus suggest that HeV exposure in this species may not result in systemic infection and virus excretion, or alternatively, may reflect assay cross-reactivity with another (unidentified) henipavirus.

Seroprevalence of three paramyxoviruses; Hendra virus, Tioman virus, Cedar virus and a rhabdovirus, Australian bat lyssavirus, in a range expanding fruit bat, the Grey-headed flying fox (Pteropus poliocephalus)

“…Hendra seropositivity was also positively associated with BCI. This contrasts with a previous study [23] which found increased seropositivity in nutritionally-stressed Little-red flying foxes but concurs with a study [10] in Black flying foxes and Grey-headed flying foxes. In our study, the body condition index of bats was significantly higher in winter than summer ( Table 2).…”

“…Late gestation was positively associated with higher Hendra virus MFI antibody levels in comparison to non-pregnant females and males. SImilar evidence is seen in serological surveys of Spectacled flying foxes [21] and Little-red flying foxes [23] which showed increased detection of Hendra virus antibodies associated with late-stage gestation or early lactation but is in contrast to recent research in Grey-headed flying foxes [10] where there is no association.…”

“…In Australia, spill-over of three viruses associated with bats of the genus Pteropus, also known as flying foxes, has led to morbidity and mortality in domestic animals and humans. They include two paramyxoviruses, Hendra virus and Menangle virus, and a rhabdovirus, Australian bat lyssavirus [6][7][8][9][10]. Research into the ecology of these viruses led subsequently to the discovery of several new paramyxoviruses, including Cedar virus, Hervey virus, Yeppoon virus, Grove virus, Teviot virus [11] and Tioman virus [12].…”

“…There is evidence to suggest that two species, namely the Black flying fox (Pteropus alecto) and the Spectacled flying fox (P. conspicillatus), play the most active role in the transmission of Hendra virus to horses [38]. Hendra virus is shed in the urine, an important vehicle for transmission in Black flying foxes [10,[38][39], and the virus has been detected in Grey-headed flying fox uterine fluid which provides evidence for possible transmission at birthing period which lasts from late September to early December [40] in this species [41,42].…”

Coronaviruses and Australian bats: a review in the midst of a pandemic

“…Zhang et al 2013;Zhou et al 2016;Schountz et al 2017), and infectious disease emergence (Gould et al 1998;Halpin et al 2000;Barr et al 2012;Kessler et al 2018) and dynamics (e.g. Field et al 2015;Plowright et al 2015;Paez et al 2017;Edson et al 2019;Peel et al 2019).…”