UNIVERSITY PARK, Pa. — Bats, which make up about a third of all mammalian species, play an important role in our ecosystem. They eat bugs and are responsible for pollinating many plants.
However, their good deeds can be overshadowed by their ability to be asymptomatic carriers of several diseases that are dangerous to humans, including Ebola and rabies.
But they were never thought to host influenza viruses, that is until researchers studying pathogen diversity in bats in South and Central America identified two new influenza viruses in fruit bats.
Subsequently, researchers in Africa found 30 percent of bats to be infected with flu viruses, although they did not show any signs of illness.
These discoveries led Suresh Kuchipudi, associate professor of virology in Penn State’s College of Agricultural Sciences, to ask if bats can be co-infected with avian and human influenza viruses, and if so, whether they can be carriers of influenza virus and have the potential to contribute to the emergence of new pandemic influenza strains by mixing these two types of influenza viruses.
To answer these questions, Kuchipudi brought together a multidisciplinary team to conduct research focusing on little brown bats, the most widely spread bat species in North America.
Kuchipudi, who works in the college’s Animal Diagnostic Laboratory said there is increasing interface between bats and humans because of wildlife trade, bush-meat hunting, deforestation and urban development.
“It’s important to determine if bats can allow infection of avian and human flu viruses and if they could then serve as ‘mixing vessels’ and perhaps create the next pandemic flu virus. Up until now, no one has ever studied influenza virus receptors in bats,” said Kuchipudi.
And the next pandemic is never out of the realm of possibility as influenza viruses always seem to be one step ahead when it comes to control. Influenza infects a wide range of domestic and wild animals and can be passed between species.
Swine flu and avian flu are examples of previous pandemics caused by influenza viruses that came from animals. Avian flu viruses continue to cause huge economic losses to the poultry industry and threaten public health globally.
“The remarkable thing about influenza viruses is the ability to constantly change and evolve,” Kuchipudi said. “ Influenza virus evolution involves mutations in the virus to gain the ability to transmit to a completely different host species.”
With assistance from the Pennsylvania Game Commission, Kuchipudi’s research team screened 20 little brown bats, 10 juvenile, and 10 adult, for the presence of influenza receptors using cutting-edge scientific methods involving lectin histochemistry, along with confocal and electron microcopy.
The team tested for the presence of two specific receptors that are responsible for helping human and avian influenza viruses attach to cells. They further investigated whether avian and human flu viruses can bind to bat tissues.
The study discovered bats have receptors in their respiratory and digestive tracts that can support binding of avian and human influenza viruses, according to Ruth Nissly, research technician and manager of Kuchipudi’s research lab.
“Having both receptors, as in the case of ducks and pigs, is believed to create conditions that enable the virus to mutate and create a new strain, which, in turn, could infect other animals, including humans,” Nissly said.
Despite these findings, Kuchipudi said there isn’t a need to sound a public health alarm or worry about a “bat flu” yet.
“While the sum of the evidence suggests that bats could play an important role in influenza epidemiology and zoonotic influenza emergence, we do not have sufficient scientific understanding needed to adequately predict which influenza strains may cause the next pandemic or what hosts they may come from,” he said.
He cited the need for more research on how influenza may manifest itself in bats, as well as for additional surveillance of wild bats.
The research was published in April 2017, in Scientific Reports, an online, open access journal from the publishers of Nature.