Faust, C. | bioRxiv Science

bioRxiv2025

Spillover of H5 influenza viruses to vampire bats at the marine-terrestrial interface

The highly pathogenic H5N1 avian influenza A virus (IAV) clade 2.3.4.4b has spread globally and spilled over into multiple mammalian species, raising concerns about its pandemic potential. In late 2022, clade 2.3.4.4b viruses devastated seabird and marine mammal populations along the Pacific coast of South America. Here, we report the first evidence of H5 IAV infections in wild bats globally, focusing on common vampire bats (Desmodus rotundus) in coastal areas of Peru. Longitudinal serological screening, stable isotope analysis and metabarcoding revealed repeated exposures to H5 IAVs in vampire bats which feed on coastal wildlife species heavily impacted by the 2.3.4.4b epizootic, but no evidence of infection in populations without access to marine prey. We further report bat gene flow between IAV-exposed and IAV-naive populations, and IAV infections in a vampire bat colony that fed on both marine and terrestrial livestock prey, providing insights into how future IAV epizootics might spread spatially within bats and between marine and terrestrial ecosystems if a bat reservoir were established. Immunohistochemistry demonstrated that the H5 haemagglutinin protein binds to the upper respiratory tract of vampire bats, suggesting bat tissue susceptibility to H5 IAVs. Finally, vampire bat-derived kidney, liver, and lung cells supported entry, replication, and egress of avian and mammalian 2.3.4.4b viruses, confirming cellular infectivity. These results illustrate how combining ecological inference and experimental virology can pinpoint the species origins and biological significance of viral spillover at species interfaces. Recurrent exposures from marine wildlife, tissue and cellular susceptibility to H5N1 IAVs, and connections to other IAV-susceptible terrestrial mammals establish the prerequisite conditions for vampire bats to spread IAVs between marine and terrestrial environments or to form a novel reservoir of highly pathogenic IAVs.

ecology↗

bioRxiv2023

Feasibility of improving manufacturability based on protein engineering

While bioactivity and a favorable safety profile for biotherapeutics is of utmost importance, manufacturability is also worth of consideration to ease the manufacturing process. Many biotherapeutics are typically expressed in mammalian cells. Process-related impurities or biological impurities like viruses and host cell proteins (HCP) are present in the harvest which have mostly acid isoelectric points and need to be removed to ensure safety for the patients. Therefore, during molecule design, an isoelectric point of the target molecule should preferably differ sufficiently from the isoelectric points of the impurities to enable an efficient and straightforward purification strategy. In this feasibility study we have evaluated the possibility to improve manufacturability by increasing the isoelectric point of the target protein. We have generated several variants of a GLP1-receptor-agonist-Fc-domain -FGF21 fusion protein and demonstrate that the critical anion exchange chromatography step can be run at high pH values with maximal product recovery theoretically allowing removal of HCP and viruses. Addressing the isoelectric point can be useful for an efficient process for removing HCP and viruses and this topic should be considered early in the research phase to ensure that other important molecule properties, e.g. safety, efficacy and expression yield are not impacted.

bioengineering↗