Egyptian Fruit Bats (Rousettus aegyptiacus) Were Resistant to Experimental Inoculation with Avian-Origin Influenza A Virus of Subtype H9N2, But Are Susceptible to Experimental Infection with Bat-Borne H9N2 Virus

Abstract

Influenza A viruses (IAV) of subtype H9N2, endemic in world-wide poultry holdings, are reported to cause spill-over infections to pigs and humans and have also contributed substantially to recent reassortment-derived pre-pandemic zoonotic viruses of concern, such as the Asian H7N9 viruses. Recently, a H9N2 bat influenza A virus was found in Egyptian fruit bats (Rousettus aegyptiacus), raising the question of whether this bat species is a suitable host for IAV. Here, we studied the susceptibility, pathogenesis and transmission of avian and bat-related H9N2 viruses in this new host. In a first experiment, we oronasally inoculated six Egyptian fruit bats with an avian-related H9N2 virus (A/layer chicken/Bangladesh/VP02-plaque/2016 (H9N2)). In a second experiment, six Egyptian fruit bats were inoculated with the newly discovered bat-related H9N2 virus (A/bat/Egypt/381OP/2017 (H9N2)). While R. aegyptiacus turned out to be refractory to an infection with H9N2 avian-type, inoculation with the bat H9N2 subtype established a productive infection in all inoculated animals with a detectable seroconversion at day 21 post-infection. In conclusion, Egyptian fruit bats are most likely not susceptible to the avian H9N2 subtype, but can be infected with fruit bat-derived H9N2. H9-specific sero-reactivities in fruit bats in the field are therefore more likely the result of contact with a bat-adapted H9N2 strain.

Molecular, ecological, and behavioral drivers of the bat-virus relationship

“…R. aegyptiacus bats have also been inoculated with avian-and bat-derived H9N2 influenza A virus (IAV) (Halwe et al, 2021). Unlike inoculation with avian-H9N2, R. aegyptiacus bats were susceptible to bat-H9N2, during which the first indication of infection was a change in body temperature (Halwe et al, 2021). Transmission of bat-H9N2 among experimentally infected R. aegyptiacus bats was evident, similarly to what has been described for Artibeus jamaicensis bats infected with bat-derived H18N11.…”

“…Recently, the eye has been associated with viral persistence in humans infected with ebolavirus, but the mechanisms that facilitate viral persistence remain unknown (Varkey et al, 2015). R. aegyptiacus bats have also been inoculated with avian-and bat-derived H9N2 influenza A virus (IAV) (Halwe et al, 2021). Unlike inoculation with avian-H9N2, R. aegyptiacus bats were susceptible to bat-H9N2, during which the first indication of infection was a change in body temperature (Halwe et al, 2021).…”

Selection and Stability Validation of Reference Gene Candidates for Transcriptional Analysis in Rousettus Aegyptiacus

“…The characteristics of these primers are shown in Table 4. Tissue samples from 12 individual bats were obtained from an animal experiment published before 76 .…”

Influenza A Viruses and Zoonotic Events—Are We Creating Our Own Reservoirs?

“…After serological studies discovered the presence of H9 antibodies in bats from Ghana [180], an H9N2 subtype was isolated from the Old World bat species Rousettus aegyptiacus in 2019 [181]. Interestingly, while Egyptian fruit bats could be experimentally infected with the bat H9N2 virus, they were resistant to infection with an avian-derived H9N2 virus [182]. Again, it is unclear whether bat-borne H9N2 can be transmitted to other species, like farm animals or humans invading the habitats of infected bats.…”