Fruit bats are the reservoir hosts for both Hendra and Nipah viruses (collectively known as henipaviruses). These viruses spill over into human and domestic animal populations causing morbidity, fatalities as well as restrictions on trade. There continue to be outbreaks of human infection with Nipah virus in Bangladesh and Hendra virus continues to spill over in Australia causing disease in horses and, sometimes, in humans. There have been 33 spill overs of HeV in Australia with over half of those occurring in 2011.
Despite these significant consequences for human and animal health, and irregular spill over patterns, little is known about the dynamics of henipavirus infection in their natural hosts. Results from experimental infections of bats are inconsistent and are complicated by a lack of prior exposure history. Captive studies have been relatively short-lived, comprised of few animals and have utilised laborious serum neutralisation testing requiring testing at Biosafety Level 4.
Here, we used the African straw-coloured fruit bat as a model to explore the dynamics of infection of henipaviruses in their natural hosts, testing for antibodies using sensitive Luminex assays that can be done within standard laboratories. By observing changes in individual antibody levels in a breeding population of approximately 80 bats over a period of 30 months we have made important observations regarding persistence of henipavirus infection in bats. These include: maternal antibody presence and waning; the apparent presence of virus transmission within small populations and fluctuation of antibody levels in females, which have important consequences for the likelihood of spill over to surrounding human populations.