Productive Propagation of Rift Valley Fever Phlebovirus Vaccine Strain MP-12 in Rousettus aegyptiacus Fruit Bats

Abstract

Rift Valley fever phlebovirus (RVFV), the causative agent of an emerging zoonotic disease in Africa and Arabia, can infect a variety of species, predominantly ruminants, camelids, and humans. While clinical symptoms are mostly absent in adult ruminants and camelids, RVFV infection may lead to a serious, sometimes fatal disease in humans. Virus transmissions between individuals and between species mainly occur through mosquito bites, but direct or even indirect contact with infectious materials may also result in infection. Although the main reservoir of the virus is not yet identified, small mammals such as rodents and bats may act as amplifying hosts. We therefore inoculated Rousettus aegyptiacus fruit bats that are abundant in northern Africa with the vaccine strain MP-12, in order to elucidate the general competence of this species for virus propagation and transmission. We were able to detect the RVFV genome in the spleen of each of these animals, and re-isolated the virus from the spleen and liver of some animals. Moreover, we were able to identify the Gc RVFV surface antigen in mild subacute multifocal necrotizing hepatic lesions of one bat which was sacrificed 7 days post exposure. These findings demonstrate that Rousettus aegyptiacus fruit bats can propagate RVFV.

Can Bats Serve as Reservoirs for Arboviruses?

“…Circumstantial evidence from field-sampled mosquitoes and bats supports the cycling of Babanki virus among bats and mosquitoes in Uganda [29], but experimental data are still lacking. For RVFV, bats evaluated in the lab have supported virus replication, and multiple populations of bats in the field have been found with neutralizing antibodies or natural infection with RVFV [1,28,29]. Additional studies are warranted on these and other viruses for which additional field or experimental data are needed to support the role of bats as a possible reservoir.…”

“…Bats of the species Miniopterus schreibersii ( n = 1) and Eptesicus capensis ( n = 2) were experimentally infected with RVFV and the M. schreibersii bat’s urine and liver tested positive for antigen [27]. A recent study by Balkema-Buschmann and colleagues experimentally infected Egyptian rousette bats ( Rousettus aegyptiacus ) with vaccine strain MP-12 and recovered infectious virus from spleen and liver of some animals [28]. Oelofsen & Van der Ryst (1999) examined 350 samples from 150 field-caught bats in Africa, yet none were positive for antigen by use of ELISA [27].…”

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

“…Bats are increasingly recognized as reservoir hosts of highly-virulent pathogens, such as Filoviruses, Lyssaviruses, Paramyxoviruses and Coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the current global pandemic 1 . Particularly, Egyptian fruit bats, Rousettus aegyptiacus, have been identi ed as putative reservoir hosts of Marburg virus 2 , Kasokero virus 3 and Sosuga virus 4 , and were shown to be susceptible to experimental challenge with SARS-CoV-2 5 and Rift valley fever phlebovirus 6 . These viruses may cause severe diseases with high mortality rates in humans.…”

Livestock Challenge Models of Rift Valley Fever for Agricultural Vaccine Testing

“…The control of mosquitoes involved in RVFV transmission is complex because there are numerous mosquito species present in endemic and non-endemic areas that are capable of virus infection and transmission [reviewed in Linthicum et al (29)], and continuous low-level transmission of RVFV to domestic and wild animals in endemic areas may also help maintain the virus. Other species that may play a role in RVFV ecology and have been reported to be susceptible to RVFV are mice, rats, shrews, dormice, and bats (35)(36)(37)(38)(39)(40). Additional wild animal species that have been investigated include the African buffalo, primates, elephants, rhinoceros, deer, and coyotes (41-45).…”