Mismatched and underrepresented: bat-virus diversity and phylogeographic bias in experimental infection studies

Despite growing interest in bat-virus interactions, experimental infection studies (EIS) remain taxonomically and geographically restricted, limiting inference about bat immunology and zoonotic risk. We performed a systematic literature search (Jan 1900-Jan 2025) and manually curated peer-reviewed primary studies of viral experimental infections in live bats and bat-derived cell lines (BdCL). From 545 candidate records we retained 127 papers (83 live-bat, 44 BdCL), comprising 315 unique bat-virus trials. We categorized host taxonomy, viral family (ICTV), and biogeographical congruence, to quantify temporal trends, taxonomic coverage, and host-virus pairing patterns. Results show stark underrepresentation: only 45 of ~1,500 bat species (3.2%) and 7 of 21 bat families appear in EIS. Pteropodidae, Vespertilionidae, Phyllostomidae, and Molossidae dominate studies, with Rousettus aegyptiacus, Tadarida brasiliensis, and Eptesicus fuscus most frequently trialed. Viral focus is uneven-Rhabdoviridae and Orthomyxoviridae (notably rabies [RABV] and influenza A [IAV]) account for many trials, and filoviruses are overrepresented in Rousettus sp. studies. By 2024, over half (57.8%) of trials used BdCL, and the proportion of live-bat experiments has declined in recent decades. Geographic coverage was uneven: high representation occurred in Arctic-Siberian, Eurasian, and North American regions, whereas Amazonian, Indo-Malayan, Australasian, Papua-Melanesian, and Madagascan regions were poorly represented. These biases constrain inference about host competence, immune diversity, and coevolutionary dynamics and risk overgeneralizing results across Chiroptera. These skews create a "mix-and-match" problem in which experimental pairings often do not reflect co-evolved host-virus relationships, limiting inference about host competence, immune tolerance, and zoonotic risk. To improve ecological relevance and generalizability, we recommend expanding taxonomic and geographic sampling, situating more work within virus native ranges, and integrating complementary in vitro and in vivo approaches alongside investments in regional biosafety infrastructure and standardized protocols. Addressing these critical gaps would better resolve the ecological and evolutionary determinants of susceptibility and tolerance in bats, improving mechanistic inference relevant to zoonotic emergence and conservation.