Characterization of Ravn virus viral shedding dynamics in experimentally infected Egyptian rousette bats (Rousettus aegypticus).

Abstract

Marburg virus (MARV) and Ravn virus (RAVV), the only two known members of the species Orthomarburgvirus marburgense (family Filoviridae), are causative agents of Marburg virus disease, a severe viral disease that typically emerges in sub-Saharan Africa and is characterized by human-to-human transmission and high case fatalities. Despite the robust characterization of MARV experimental infection in Egyptian rousette bats (ERBs; Rousettus aegyptiacus; common name: Egyptian rousettes), a natural MARV reservoir, experimental infection with RAVV in ERBs has not been completed. Here, we experimentally infect 12 ERBs with RAVV and quantify viral loads in blood, oral swabs, and rectal swabs over a 21-day timeline with serological and cumulative shedding data and baseline clinical parameters. Compared to previously described experimental MARV infection in ERBs, these bats experimentally inoculated with RAVV had significantly higher and prolonged rectal viral shedding loads, as well as significantly prolonged oral shedding and higher peak viremia. All ERBs seroconverted by 21 days post-infection. Additionally, all ERBs demonstrated marked heterogeneity in RAVV viral shedding loads consistent with the Pareto Principle and viral "supershedders." Our results introduce the possibility of variation in transmission dynamics and subsequent spillover differences between RAVV and MARV.IMPORTANCERavn virus, along with Marburg virus, causes severe viral disease in humans with high fatality but little to no clinical disease in its reservoir host, the Egyptian rousette bat. Our findings provide important insights into how Ravn virus behaves in its natural reservoir host, showing that Ravn virus infection followed a similar timeline to Marburg virus infection, with virus detected in blood, saliva, and feces. However, Ravn virus-infected bats had higher levels of viral shedding and shed the virus for a longer period, particularly in feces, compared to Marburg virus. These differences in viral shedding may impact the spread of the virus within bat populations and potentially alter the likelihood of spillover into humans, non-human primates, and other animal species. These insights are crucial for understanding Ravn virus maintenance in its bat reservoir and improving our ability to mitigate or prevent future human outbreaks.