Expanded diversity of novel hemoplasmas in rare and undersampled Neotropical bats

Geographically widespread and novel hemotropic mycoplasmas and bartonellae in Mexican free-tailed bats and sympatric North American bat species

Bacterial pathogens remain poorly characterized in bats, especially in North America. We describe novel (and in some cases panmictic) hemoplasmas (10.1% positivity) and bartonellae (25.6% positivity) across three colonies of Mexican free-tailed bats (Tadarida brasiliensis), a partially migratory species that can seasonally travel hundreds of kilometers. Molecular analyses identified three novel Candidatus hemoplasma species most similar to another novel Candidatus species in Neotropical molossid bats. We also detected novel hemoplasmas in sympatric cave myotis (Myotis velifer) and pallid bats (Antrozous pallidus), with sequences in the latter 96.5% related to Candidatus Mycoplasma haematohominis. We identified nine Bartonella genogroups, including those in cave myotis with 96.1% similarity to Candidatus Bartonella mayotimonensis. We also detected Bartonella rochalimae in migratory Mexican free-tailed bats, representing the first report of this human pathogen in the Chiroptera. Monthly sampling of migratory Mexican free-tailed bats during their North American occupancy period also revealed significant seasonality in infection for both bacterial pathogens, with prevalence increasing following spring migration, peaking in the maternity season, and declining into fall migration. The substantial diversity and seasonality of hemoplasmas and bartonellae observed here suggest that additional longitudinal, genomic, and immunological studies in bats are warranted to inform One Health approaches.

IMPORTANCE

Bats have been intensively sampled for viruses but remain mostly understudied for bacterial pathogens. However, bacterial pathogens can have significant impacts on both human health and bat morbidity and even mortality. Hemoplasmas and bartonellae are facultative intracellular bacteria of special interest in bats, given their high prevalence and substantial genetic diversity. Surveys have also supported plausible zoonotic transmission of these bacteria from bats to humans, including Candidatus Mycoplasma haematohominis and Candidatus Bartonella mayotimonensis. Greater characterization of these bacteria across global bat diversity (over 1,480 species) is therefore warranted to inform infection risks for both bats and humans, although little surveillance has thus far been conducted in North American bats. We here describe novel (and in some cases panmictic) hemoplasmas and bartonellae across three colonies of Mexican free-tailed bats and sympatric bat species. We find high genetic diversity and seasonality of these pathogens, including lineages closely related to human pathogens, such as Bartonella rochalimae.

Studying bats using a One Health lens: bridging the gap between bat virology and disease ecology

Accumulating data suggest that some bat species host emerging viruses that are highly pathogenic in humans and agricultural animals. Laboratory-based studies have highlighted important adaptations in bat immune systems that allow them to better tolerate viral infections compared to humans. Simultaneously, ecological studies have discovered critical extrinsic factors, such as nutritional stress, that correlate with virus shedding in wild-caught bats. Despite some progress in independently understanding the role of bats as reservoirs of emerging viruses, there remains a significant gap in the molecular understanding of factors that drive virus spillover from bats. Driven by a collective goal of bridging the gap between the fields of bat virology, immunology, and disease ecology, we hosted a satellite symposium at the 2024 American Society for Virology meeting. Bringing together virologists, immunologists, and disease ecologists, we discussed the intrinsic and extrinsic factors such as virus receptor engagement, adaptive immunity, and virus ecology that influence spillover from bat hosts. This article summarizes the topics discussed during the symposium and emphasizes the need for interdisciplinary collaborations and resource sharing.

Geographically widespread and novel hemotropic mycoplasmas and bartonellae in Mexican free-tailed bats and sympatric North American bat species

Bacterial pathogens remain poorly characterized in bats, especially in North America. We describe novel (and in some cases panmictic) hemoplasmas (10.5% positivity) and bartonellae (25.5% positivity) across three colonies of Mexican free-tailed bats (Tadarida brasiliensis), a partially migratory species that can seasonally travel hundreds of kilometers. Molecular analyses identified three novel Candidatus hemoplasma species most similar to another novel Candidatus species in Neotropical molossid bats. We also detected novel hemoplasmas in sympatric cave myotis (Myotis velifer) and pallid bats (Antrozous pallidus), with sequences in the latter 96.5% related to C. Mycoplasma haemohominis. We identified nine Bartonella genogroups, including those in cave myotis with 96.7% similarity to C. Bartonella mayotimonensis. We also detected Bartonella rochalimae in migratory Mexican free-tailed bats, representing the first report of this human pathogen in the Chiroptera. The seasonality and diversity of these bacteria observed here suggest that additional longitudinal, genomic, and immunological studies in bats are warranted.

Multi-locus sequence analysis of 'Candidatus Mycoplasma haematomacacae' in free-ranging macaques from Thailand suggestive of a closer relationship to hemotropic mycoplasmas in capuchins and potential origin from bats

Although 'Candidatus Mycoplasma haematomacacae' (formerly known as 'Candidatus Mycoplasma haemomacaque') has been reported on extensively in macaques from Thailand, the USA, Japan, and Brazil, its genetic characterization has primarily been restricted to the 16S rRNA sequences with no exploration on multi-locus sequence analysis. The primary goal of this study was to characterize 'Ca. M. haematomacacae' among Thai macaques based on multiple genetic markers. Between April 2018 and November 2021, blood samples were taken from 580 free-ranging macaques (560 Macaca fascicularis and 20 Macaca nemestrina) in 15 locations encompassing 10 provinces throughout Thailand. Using the conventional PCR assay targeting the 16S ribosomal RNA (16S rRNA) gene, 338 out of 580 macaques (58.27 %) tested hemoplasma-positive. Of these, 40 positive samples were further subjected to DNA sequencing, and all were identified as 'Ca. M. haematomacacae'. Subsequently, the partial nucleotide sequences of 23S ribosomal RNA (23S rRNA) and RNase P RNA (rnpB) genes of this particular hemoplasma species were amplified through nested PCR assay. The analysis of multi-locus genetic markers revealed that the 23S rRNA and rnpB sequences exhibited higher levels of genetic diversity than the 16S rRNA sequences. Furthermore, the 16S rRNA analyses demonstrated that 'Ca. M. haematomacacae' infecting Old World monkeys (Macaca spp.) was most closely related to hemotropic Mycoplasma spp. in black-capped capuchins (Sapajus apella) and Marcgrave's capuchins (Sapajus flavius) from Brazil, as well as establishing a common ancestor clade with hemotropic Mycoplasma spp. from the Neotropical bats in Belize and Peru and an Old World bat in Spain. The 23S rRNA analyses likewise evidenced that 'Ca. M. haematomacacae' formed a sister clade with hemotropic Mycoplasma spp. in Neotropical bats from Belize and Panama. Thus, the present findings, based on multi-locus sequence analysis, suggest a potential origin of 'Ca. M. haematomacacae' from Neotropical and Old World bats. To the best of the authors' knowledge, this study provided the largest dataset so far of multi-locus genetic sequences of 'Ca. M. haematomacacae' isolated from Thai macaques and enhanced the accuracy of phylogenetic analyses, providing insights into their origins among hemotropic Mycoplasma spp. discovered worldwide.

Bat cellular immunity varies by year and dietary habit amidst land conversion

Monitoring the health of wildlife populations is essential in the face of increased agricultural expansion and forest fragmentation. Loss of habitat and habitat degradation can negatively affect an animal's physiological state, possibly resulting in immunosuppression and increased morbidity or mortality. We sought to determine how land conversion may differentially impact cellular immunity and infection risk in Neotropical bats species regularly infected with bloodborne pathogens, and to evaluate how effects may vary over time and by dietary habit. We studied common vampire bats (Desmodus rotundus), northern yellow-shouldered bats (Sturnira parvidens) and Mesoamerican mustached bats (Pteronotus mesoamericanus), representing the dietary habits of sanguivory, frugivory and insectivory respectively, in northern Belize. We compared estimated total white blood cell count, leukocyte differentials, neutrophil to lymphocyte ratio and infection status with two bloodborne bacterial pathogens (Bartonella spp. and hemoplasmas) of 118 bats captured in a broadleaf, secondary forest over three years (2017-2019). During this period, tree cover decreased by 14.5% while rangeland expanded by 14.3%, indicating increasing habitat loss and fragmentation. We found evidence for bat species-specific responses of cellular immunity between years, with neutrophil counts significantly decreasing in S. parvidens from 2017 to 2018, but marginally increasing in D. rotundus. However, the odds of infection with Bartonella spp. and hemoplasmas between 2017 and 2019 did not differ between bat species, contrary to our prediction that pathogen prevalence may increase with land conversion. We conclude that each bat species invested differently in cellular immunity in ways that changed over years of increasing habitat loss and fragmentation. We recommend further research on the interactions between land conversion, immunity and infection across dietary habits of Neotropical bats for informed management and conservation.