In the intricate web of viral ecology, bats have long been recognized as pivotal reservoirs for a myriad of viruses, including the paramyxoviruses whose members pose serious threats to animal and human health. Yet, despite their acknowledged importance, the evolutionary origins and pathways of paramyxoviruses within the genus Morbillivirus, which includes the notorious measles virus, remain enshrouded in mystery. Recent research spearheaded by Jo, Moreira-Soto, Almeida Campos, and colleagues sheds compelling new light on these enigmatic viruses, revealing a diverse and dynamic morbillivirus landscape intertwined with Neotropical bat species and non-human primates (NHPs) in Central and South America.
The study harnessed an extensive dataset collected over a span of 14 years, during which field surveys and data mining techniques converged to unveil six highly divergent morbilliviruses circulating in the wild populations of bats and primates in Brazil and Costa Rica. These discoveries were far from marginal; they emerged from screening an impressive total of 1,629 bats, of which 38 individuals tested positive by reverse transcription polymerase chain reaction (RT–PCR), and 1,370 non-human primates, 13 of which also harbored viral RNA. The presence of these viruses in wild hosts underscores the complex and prolonged interaction between morbilliviruses and their Neotropical vertebrate reservoirs, potentially predating contemporary disease emergence patterns.
One of the most striking revelations was the sheer viral load detected in infected animals. Quantification of viral RNA revealed concentrations reaching up to 10^9 RNA copies per gram of tissue, a formidable viral abundance that, coupled with the presence of viral RNA staining in multiple organs, strongly suggests systemic infection within these reservoir hosts. Such systemic engagement indicates not only efficient replication but also points towards a well-established virus-host relationship, where morbilliviruses can persist and propagate without necessarily inducing terminal disease in the reservoir populations.
Delving deeper into the immunological landscape, the research team focused on vampire bats, a species with known ecological and epidemiological significance in the Neotropics. Contrary to models where viral infection precipitates high mortality, nearly 36% of the 117 tested vampire bats exhibited neutralizing antibodies against an isolated primary vampire bat morbillivirus strain. This antibody prevalence indicates frequent exposure to morbilliviruses and suggests that infections within these bat populations tend to be non-fatal, hinting at a co-evolved host-pathogen balance facilitating viral maintenance and transmission.
The molecular underpinnings of viral entry and antigenic conservation were interrogated via in vitro assays designed to elucidate receptor usage. Specifically, bat CD150 (SLAMF1), a cellular receptor pivotal for morbillivirus entry, was scrutinized to discern host-virus interactions. These assays revealed that the bat-associated morbilliviruses employ bat CD150 for cellular entry, reminiscent of classic morbilliviral infection strategies. Additionally, partial cross-neutralization assays employing heterologous sera corroborated a conserved antigenic architecture among bat-associated viruses, implying that despite sequence divergence, critical viral epitopes remain sufficiently preserved to elicit cross-reactive immune responses.
Intriguingly, primate-associated morbilliviruses diverged functionally from their bat counterparts in cellular receptor usage. While non-human primate morbilliviruses effectively utilized human CD150 and nectin-4 receptors—both key for cell entry and viral dissemination—bat-associated viruses failed to engage these receptors efficiently. This disparity intimates a differential zoonotic potential, wherein NHP-associated morbilliviruses may pose an elevated risk of spillover into human populations relative to their bat-borne relatives.
Beyond acute infection dynamics, the team executed careful macroevolutionary reconstructions tracing morbilliviral diversification across host lineages. These phylogenetic reconstructions uncovered a predominant association with Neotropical bat hosts during viral evolution, underscoring bats’ pivotal role not only as viral reservoirs but as crucibles of morbilliviral diversification. Remarkably, certain morbilliviral lineages exhibited host-shift events from bats to other species such as Mexican pigs and Brazilian non-human primates. These host jumps highlight the plasticity of morbilliviruses and their capacity to breach species barriers, a trait integral to viral emergence and pandemic potential.
The implications of identifying such host-shift events are far-reaching. Livestock and primate populations represent interfaces where zoonotic transmissions could be amplified, especially in environmentally pressured Neotropical biodiversity hotspots where human-wildlife-livestock interactions are increasingly frequent. Hence, the evidence for bat-origin morbilliviruses infiltrating these populations raises alarms for both animal health and potential zoonotic spillover into human communities, necessitating urgent surveillance.
In light of these findings, the authors advocate for intensified surveillance campaigns targeting wildlife reservoirs—especially bats and non-human primates—in the Neotropics. Such efforts would entail systematic sampling and viral diagnostics aimed at unearthing elusive morbilliviral variants that may lurk undetected. Complementing surveillance, experimental risk assessments that evaluate the infectivity and pathogenicity of emerging morbilliviruses across species boundaries are critical to discern their zoonotic threat level and inform risk mitigation.
Intervention strategies, although currently in nascent stages for morbilliviruses outside the classical measles framework, must be recalibrated to consider the rich viral diversity and ecological complexity uncovered. Vaccine development, antiviral therapeutics, and ecological management practices might all converge in future efforts to preempt harmful host shifts. Notably, the conserved antigenic features identified could streamline vaccine design strategies that offer cross-protective immunity against a spectrum of bat-origin morbilliviruses.
This research not only unravels the complex evolutionary tapestry of morbilliviruses but also challenges conventional perspectives on virus-host co-evolution and zoonotic potential within the paramyxovirus family. By pinpointing a bat-centric origin for diverse morbillivirus lineages and illuminating the molecular determinants governing host specificity, the study propels forward our understanding of viral emergence mechanisms and underscores the necessity of integrating ecological, virological, and immunological disciplines in combating forthcoming infectious disease threats.
As ecosystems continue to experience anthropogenic pressures, the disruption of natural reservoirs and increased interspecies contacts may accelerate the incidence of viral host shifts, positioning morbilliviruses as potential candidates for emerging infectious diseases. Research such as this paves the way for proactive approaches grounded in ecological surveillance and molecular virology, enabling early detection and intervention before outbreaks can bloom into global health crises.
In sum, the intricate dance between Neotropical bats, morbilliviruses, and incidental hosts reveals both the ancient lineage of these viruses and their ongoing evolutionary agility. By mapping these viral trajectories and decoding the receptor-use patterns that govern host susceptibility, scientists are better equipped to forecast and forestall the next chapter of morbillivirus emergence. The nexus of wildlife ecology and virology illuminated by this study calls for collaborative, multidisciplinary strategies to safeguard human and animal health amid a rapidly changing biosphere.
Subject of Research: Ecology and evolutionary dynamics of morbilliviruses in Neotropical bats and non-human primates.
Article Title: Ecology and evolutionary trajectories of morbilliviruses in Neotropical bats.
Article References:
Jo, W.K., Moreira-Soto, A., Almeida Campos, A.C. et al. Ecology and evolutionary trajectories of morbilliviruses in Neotropical bats. Nat Microbiol (2025). https://doi.org/10.1038/s41564-025-02005-8
Image Credits: AI Generated
