Bats and viruses: a death-defying friendship

Going batty: US bat imports raise concerns for species conservation and human health

The relationship between bats (order: Chiroptera) and humans is complex, highly contextualized across the globe, and dynamic. We assessed the United States (US) importation of live bats, as well as bat-derived products, from bat conservation and human health (zoonotic disease) perspectives. From 2015 to 2023, at least 284 bat species were imported into the US from at least 106 countries of origin, predominantly Indonesia. Scientific use was the most frequently declared import purpose. According to the IUCN Red List, thirty-seven of these bat species are extinction vulnerable. An investigation of US-based e-commerce platforms for live bats and bat-derived products located ads for 28 bat species for sale, including one for which trade is prohibited. Considering zoonotic spillover risk, we identified host-pathogen associations between 106 reported bat species imports and 45 zoonotic RNA viruses, representing 11 viral families. Twenty-five of the 45 viruses for which we found bat associations are listed as pathogens of concern by the World Health Organization or by US federal agencies. Rabies is the most hosted virus among bat species in our studies, followed by Dengue virus. We discuss the implications of our findings, as well as make recommendations for improving the science and policy necessary to mitigate trade-driven risks to bat and human populations. There is a need for ongoing assessments of bat population viability, as well as pathogen surveillance along the bat trade pathway. Greater attention by regulatory agencies is warranted to mitigate bat conservation and zoonotic pathogen risks apparent in e-commerce pathways. The Convention on the International Trade in Endangered Species of Fauna and Flora (CITES) and other multilateral environmental agreements could bring this issue to the forefront of member countries as part of the emerging global agenda at the conservation-zoonotic disease interface.

Rabies virus, Bartonella koehlerae and Leishmania infantum coinfection in a black Myotis (Myotis nigricans) from southeastern Brazil

The aim of this study was to investigate the presence of important zoonotic agents in Brazil in urban bats and to evaluate the existence of coinfections in bats diagnosed with rabies. In 2021, organ samples from 52 bats from urban areas in southeastern Brazil were used to diagnose rabies and other zoonoses occurring in the region. The positive samples were sequenced, characterized and included in GenBank. A co-infection involving the rabies virus, Bartonella koehlerae, and Leishmania infantum was identified in a Black Myotis bat collected from a household in São Manuel, a city endemic for visceral leishmaniasis. Phylogenetic analysis showed similarity between the RABV sequence obtained and reference sequences from humans and wild canids, as well as confirming the identity of the Bartonella and Leishmania species detected. To the best of our knowledge, this is the first report of a bat co-infected with rabies virus, B. koehlerae, and L. infantum. The co-infection of three important pathogens in a Black Myotis highlights the multifaceted role of neotropical bats as reservoirs of zoonotic agents. This unprecedented finding reinforces the potential of these animals to contribute to the transmission dynamics of viral, bacterial and protozoan pathogens, and the importance of molecular surveillance in bats.

In vitro characterization of the antiviral activity of Bat Interferon-Induced protein with tetratricopeptide repeats 5 (bat IFIT5) against bat-associated rabies virus

Bats are important reservoirs of zoonotic viruses, including the rabies virus (RABV), which causes rabies, a significant and fatal disease. In Brazil, RABV has been detected in several bat species. Interferon-induced protein with tetratricopeptide repeats 5 (IFIT5) is part of a group of interferon-stimulated genes (ISGs) known for their antiviral activity. This study investigated the interaction between batIFIT5 and different genetic lineages of RABV. The batIFIT5 was expressed in HEK-293T cells, which were infected with RABV genetic lineages isolated from Eptesicus furinalis (IP 964/06) and Tadarida brasiliensis (IP 3214/19), at varying infectious doses (pure, 100, 10, and 1). Direct immunofluorescence was performed to assess the effect of batIFIT5 on virus replication through the counting of fluorescent foci. Subsequently, after the expression of batIFIT5, 1 MOI was selected and used to evaluate the potential antiviral effect. Immunofluorescence was performed 24 and 48 h after infection. As a result, the viral concentration remained similar in the presence of batIFIT5 across distinct infectious doses. After infection with 1 MOI, a 30% reduction in infection rates was observed, particularly for the IP 3214/19 isolate after 24 h. These results highlight the potential antiviral role of IFIT5 against RABV infection.

Genomics of novel influenza A virus (H18N12) in bats, Caribe Colombia

Influenza viruses are highly capable of mutating and adapting in mammalian hosts. While these viruses have been extensively studied in birds, research on their presence in bats has been limited. However, influenza viruses circulating in bats have shown notable molecular divergence. The present study aimed to characterize the phylogenetic, evolutionary, and antigenic relationships of an influenza A virus detected in the fishing bat Noctilio albiventris. As part of a pathogen surveillance study of public health interest, 159 rectal samples were collected from bats in the Colombian Caribbean. The samples were sequenced using RNA-Seq. A genome (eight viral contigs) associated with the Orthomyxoviridae family was identified in a pool. Most segments showed approximately 90% similarity with H18N11, except for the neuraminidase. Analysis of the N protein shows that occupies a basal position relative to the N11 subtype, with its divergence date estimated to be approximately 50 years earlier than the earliest reported N11 sequence. 3D modeling identified three mutations (K363R, T242K, and I139V), which may enhance interaction with the HLA-DR of bats. The analyses and antigenic divergence observed in the N protein of N. albiventris suggests the existence of a new subtype (H18N12) with unknown pathogenicity, which requires further investigation.

Bat coronavirus surveillance across different habitats in Yucatán, México

Bats, which play a vital role in maintaining ecosystems, are also known as natural reservoirs of coronaviruses (CoVs), thus have raised concerns about their potential transmission to humans, particularly in light of the emergence of MERS-CoV, SARS-CoV, and SARS-CoV-2. The increasing impact of human activities and ecosystem modifications is reshaping bat community structure and ecology, heightening the risk of the emergence of potential epidemics. Therefore, continuous monitoring of these viruses in bats is necessary. Despite the rich diversity of bats species in México, few studies have been conducted to search for CoVs in these group of mammals. In the present study we conducted CoV surveillance across previously unexplored sites in the state of Yucatán, a state located within the ecologically diverse Yucatán Peninsula, a tropical region undergoing pronounced anthropogenic changes, including deforestation, agricultural expansion and urbanization. We captured 191 bats between 2021 and 2022 in three different habitats: diversified rural (Tzucacab), rural (Tizimín) and urban (Mérida). Molecular analyses had revealed a 5.4% CoV prevalence, with the diversified rural site exhibiting a notably elevated rate (26.3%). Subsequent sequencing and phylogenetic assessment revealed four distinct Alphacoronavirus genotypes, indicating host-specific clustering among Phyllostomidae bats. Notably, one was detected for the first time in a Sturnira species. Our findings suggest a reduced likelihood of transmission of these viruses to humans or other species, evidenced by clustering patterns and sequence dissimilarity with known CoVs. We emphasize that maintaining sustained virus surveillance in bats is crucial to understanding viral diversity and identifying potential risks to human and animal health.

Serological Evidence of Hantavirus in Bats from the Brazilian Atlantic Forest: An Investigation of Seroreactivity and Cross-Reactivity of Neotropical Bat Samples Using Nucleoproteins of Rodent- and Bat-Borne Hantaviruses

Hantaviruses are zoonotic pathogens associated with severe human diseases such as hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Despite the extensive study of rodent-borne hantaviruses, research on bat-associated hantaviruses remains limited. This study aimed to investigate the seroprevalence and cross-reactivity of neotropical bat samples with rodent- and bat-associated recombinant hantavirus nucleoproteins (rNPs) to improve hantavirus surveillance in the Brazilian Atlantic Forest. The studied bat population consisted of 336 blood samples collected over nearly a decade in five Brazilian states (Bahia, Rio de Janeiro, Santa Catarina, Paraná, and Minas Gerais). Antibodies were detected using IgG ELISA assays with rNPs from bat-borne Mobatvirus xuansonense (XSV) and Loanvirus brunaense (BRNV) and the rodent-borne hantaviruses Orthohantavirus andesense (ANDV) and Orthohantavirus seoulense (SEOV). Results indicated a higher seroprevalence for the BRNV rNP (36.6%) compared to ANDV (7.4%), SEOV (5.7%), and XSV (0.6%). The high sensitivity of the BRNV rNP and the cross-reactivity observed with the ANDV rNP, the main protein used for serological tests in the Americas, indicates that BRNV rNP is a better antigen for the accurate detection of antibodies against hantaviruses in Brazilian bats. These findings underscore the presence of unknown hantaviruses antigenically similar to BRNV in Brazilian bat populations and highlight the urgent need for identifying better antigens for comprehensive hantavirus monitoring in bats.

A tale of endurance: bats, viruses and immune dynamics

The emergence of highly zoonotic viral infections has propelled bat research forward. The viral outbreaks including Hendra virus, Nipah virus, Marburg virus, Ebola virus, Rabies virus, Middle East respiratory syndrome coronavirus, SARS-CoV and the latest SARS-CoV-2 have been epidemiologically linked to various bat species. Bats possess unique immunological characteristics that allow them to serve as a potential viral reservoir. Bats are also known to protect themselves against viruses and maintain their immunity. Therefore, there is a need for in-depth understanding into bat-virus biology to unravel the major factors contributing to the coexistence and spread of viruses.

Evolution of T cells in the cancer-resistant naked mole-rat

Naked mole-rats (NMRs) are best known for their extreme longevity and cancer resistance, suggesting that their immune system might have evolved to facilitate these phenotypes. Natural killer (NK) and T cells have evolved to detect and destroy cells infected with pathogens and to provide an early response to malignancies. While it is known that NMRs lack NK cells, likely lost during evolution, little is known about their T-cell subsets in terms of the evolution of the genes that regulate their function, their clonotypic diversity, and the thymus where they mature. Here we find, using single-cell transcriptomics, that NMRs have a large circulating population of γδT cells, which in mice and humans mostly reside in peripheral tissues and induce anti-cancer cytotoxicity. Using single-cell-T-cell-receptor sequencing, we find that a cytotoxic γδT-cell subset of NMRs harbors a dominant clonotype, and that their conventional CD8 αβT cells exhibit modest clonotypic diversity. Consistently, perinatal NMR thymuses are considerably smaller than those of mice yet follow similar involution progression. Our findings suggest that NMRs have evolved under a relaxed intracellular pathogenic selective pressure that may have allowed cancer resistance and longevity to become stronger targets of selection to which the immune system has responded by utilizing γδT cells.

Molecular detection of Babesia vesperuginis in bats from Lithuania

Babesia vesperuginis is an intraerythrocytic protozoan parasite that circulates among bats and ticks in many countries worldwide. However, the distribution of B. vesperuginis in the Baltic region has not been studied. A total of 86 dead bats from eight different species were collected and screened for Babesia spp. using real-time PCR. Overall, 52.3% (45/86) of the bats were found positive for Babesia spp. The prevalence of Babesia spp. in different organs varied, with the highest prevalence observed in heart tissues (37.0%) and the lowest in liver tissues (22.2%). However, the observed differences in prevalence among organs were not statistically significant. Blood samples from 125 bats of nine different species were also analyzed for Babesia spp. prevalence using real-time PCR and nested PCR. The results showed a prevalence of 35.2% and 22.4%, respectively. Moreover, 28.3% (17/60) of the examined blood samples were confirmed positive for Babesia spp. through blood smear analysis. The total of 32 partial sequences of the 18S rRNA gene derived in this study were 100% identical to B. vesperuginis sequences from GenBank. In eight species of bats, Pipistrellus nathusii, Pipistrellus pipistrellus, Pipistrellus pygmaeus, Vespertilio murinus, Eptesicus nilssonii, Eptesicus serotinus, Myotis daubentonii and Nyctalus noctula, Babesia parasites were identified. In E. nilssonii, Babesia spp. was identified for the first time.

Molecular surveillance of potential SARS-CoV-2 reservoir hosts in wildlife rehabilitation centers

BACKGROUND

The COVID-19 pandemic, caused by SARS-CoV-2 infection, has become the most devastating zoonotic event in recent times, with negative impacts on both human and animal welfare as well as on the global economy. Although SARS-CoV-2 is considered a human virus, it likely emerged from animals, and it can infect both domestic and wild animals. This constitutes a risk for human and animal health including wildlife with evidence of SARS-CoV-2 horizontal transmission back and forth between humans and wild animals.

AIM

Molecular surveillance in different wildlife rehabilitation centers and wildlife associated institutions in Chile, which are critical points of animal-human interaction and wildlife conservation, especially since the aim of wildlife rehabilitation centers is to reintroduce animals to their original habitat.

MATERIALS AND METHODS

The survey was conducted in six WRCs and three wildlife associated institutions. A total of 185 samples were obtained from 83 individuals belonging to 15 different species, including vulnerable and endangered species. Each specimen was sampled with two different swabs: one oropharyngeal or nasopharyngeal according to the nostril diameter, and/or a second rectal sample. RNA was extracted from the samples and two different molecular assays were performed: first, a conventional RT-PCR with pan-coronavirus primers and a second SARS-CoV-2 qPCR targeting the N and S genes.

RESULTS

All 185 samples were negative for SARS-CoV-2.

CLINICAL RELEVANCE

This study constitutes the first report on the surveillance of SARS-CoV-2 from wildlife treated in rehabilitation centers in Chile, and supports the biosafety procedures adopted in those centers.

First Report of Alphacoronavirus Circulating in Cavernicolous Bats from Portugal

The emergence of novel coronaviruses (CoVs) has emphasized the need to understand their diversity and distribution in animal populations. Bats have been identified as crucial reservoirs for CoVs, and they are found in various bat species worldwide. In this study, we investigated the presence of CoVs of four cavernicolous bats in six locations in the centre and south of Portugal. We collected faeces, anal, and buccal swab samples, as well as air samples from the locations using a Coriolis air sampler. Our results indicate that CoVs were more readily detected in faecal samples compared to anal and buccal swab samples. No CoVs were detected in the air samples. Phylogenetic analysis showed that the detected viruses belong to the Alphacoronavirus genus. This study represents the first report of Alphacoronaviruses circulating in bats in Portugal and highlights the importance of continuous surveillance for novel CoVs in bat populations globally. Ongoing surveillance for CoVs in bat populations is essential as they are a vital source of these viruses. It is crucial to understand the ecological relationships between animals, humans, and the environment to prevent and control the emergence and transmission of infectious diseases. Further ecological studies are needed to investigate the factors contributing to the emergence and transmission of zoonotic viruses.

Inferring the disruption of rabies circulation in vampire bat populations using a betaherpesvirus-vectored transmissible vaccine

Transmissible vaccines are an emerging biotechnology that hold prospects to eliminate pathogens from wildlife populations. Such vaccines would genetically modify naturally occurring, nonpathogenic viruses ("viral vectors") to express pathogen antigens while retaining their capacity to transmit. The epidemiology of candidate viral vectors within the target wildlife population has been notoriously challenging to resolve but underpins the selection of effective vectors prior to major investments in vaccine development. Here, we used spatiotemporally replicated deep sequencing to parameterize competing epidemiological mechanistic models of Desmodus rotundus betaherpesvirus (DrBHV), a proposed vector for a transmissible vaccine targeting vampire bat-transmitted rabies. Using 36 strain- and location-specific time series of prevalence collected over 6 y, we found that lifelong infections with cycles of latency and reactivation, combined with a high R0 (6.9; CI: 4.39 to 7.85), are necessary to explain patterns of DrBHV infection observed in wild bats. These epidemiological properties suggest that DrBHV may be suited to vector a lifelong, self-boosting, and transmissible vaccine. Simulations showed that inoculating a single bat with a DrBHV-vectored rabies vaccine could immunize >80% of a bat population, reducing the size, frequency, and duration of rabies outbreaks by 50 to 95%. Gradual loss of infectious vaccine from vaccinated individuals is expected but can be countered by inoculating larger but practically achievable proportions of bat populations. Parameterizing epidemiological models using accessible genomic data brings transmissible vaccines one step closer to implementation.

Bats-associated beta-coronavirus detection and characterization: First report from Pakistan

Bats remains as reservoirs for highly contagious and pathogenic viral families including the Coronaviridae, Filoviridae, Paramyxoviruses, and Rhabdoviridae. Spill over of viral species (SARS-CoV, MERS-CoV & SARS-CoV2) from bats (as a possible potential reservoirs) have recently caused worst outbreaks. Early detection of viral species of pandemic potential in bats is of great importance. We detected beta coronaviruses in the studied bats population (positive samples from Rousettus leschenaultia) and performed the evolutionary analysis, amino acid sequence alignment, and analysed the 3-Dimentional protein structure. We detected the coronaviruses for the first time in bats from Pakistan. Our analysis based on RdRp partial gene sequencing suggest that the studied viral strains are closely related to MERS-CoV-like viruses as they exhibit close structure similarities (with few substitutions) and also observed a substitution in highly conserved SDD in the palm subdomain of motif C to ADD, when compared with earlier reported viral strains. It could be concluded from our study that coronaviruses are circulating among the bat's population in Pakistan. Based on the current findings, we suggest large scale screening procedures of bat virome across the country to detect potential pathogenic viral species.

Mechanisms and clinical evidence to support melatonin's use in severe COVID-19 patients to lower mortality

The fear of SARS-CoV-2 infection is due to its high mortality related to seasonal flu. To date, few medicines have been developed to significantly reduce the mortality of the severe COVID-19 patients, especially those requiring tracheal intubation. The severity and mortality of SARS-CoV-2 infection not only depend on the viral virulence, but are primarily determined by the cytokine storm and the destructive inflammation driven by the host immune reaction. Thus, to target the host immune response might be a better strategy to combat this pandemic. Melatonin is a molecule with multiple activities on a virus infection. These include that it downregulates the overreaction of innate immune response to suppress inflammation, promotes the adaptive immune reaction to enhance antibody formation, inhibits the entrance of the virus into the cell as well as limits its replication. These render it a potentially excellent candidate for treatment of the severe COVID-19 cases. Several clinical trials have confirmed that melatonin when added to the conventional therapy significantly reduces the mortality of the severe COVID-19 patients. The cost of melatonin is a small fraction of those medications approved by FDA for emergency use to treat COVID-19. Because of its self-administered, low cost and high safety margin, melatonin could be made available to every country in the world at an affordable cost. We recommend melatonin be used to treat severe COVID-19 patients with the intent of reducing mortality. If successful, it would make the SARS-CoV-2 pandemic less fearful and help to return life back to normalcy.

Transnational and Transdisciplinary Lessons from the COVID-19 Pandemic

On 7 January 2020, China identified a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [...]