David Moran

A distinct lineage of influenza A virus from bats

Influenza A virus reservoirs in animals have provided novel genetic elements leading to the emergence of global pandemics in humans. Most influenza A viruses circulate in waterfowl, but those that infect mammalian hosts are thought to pose the greatest risk for zoonotic spread to humans and the generation of pandemic or panzootic viruses. We have identified an influenza A virus from little yellow-shouldered bats captured at two locations in Guatemala. It is significantly divergent from known influenza A viruses. The HA of the bat virus was estimated to have diverged at roughly the same time as the known subtypes of HA and was designated as H17. The neuraminidase (NA) gene is highly divergent from all known influenza NAs, and the internal genes from the bat virus diverged from those of known influenza A viruses before the estimated divergence of the known influenza A internal gene lineages. Attempts to propagate this virus in cell cultures and chicken embryos were unsuccessful, suggesting distinct requirements compared with known influenza viruses. Despite its divergence from known influenza A viruses, the bat virus is compatible for genetic exchange with human influenza viruses in human cells, suggesting the potential capability for reassortment and contributions to new pandemic or panzootic influenza A viruses.

Bats are a major natural reservoir for hepaciviruses and pegiviruses

Although there are over 1,150 bat species worldwide, the diversity of viruses harbored by bats has only recently come into focus as a result of expanded wildlife surveillance. Such surveys are of importance in determining the potential for novel viruses to emerge in humans, and for optimal management of bats and their habitats. To enhance our knowledge of the viral diversity present in bats, we initially surveyed 415 sera from African and Central American bats. Unbiased high-throughput sequencing revealed the presence of a highly diverse group of bat-derived viruses related to hepaciviruses and pegiviruses within the family Flaviridae. Subsequent PCR screening of 1,258 bat specimens collected worldwide indicated the presence of these viruses also in North America and Asia. A total of 83 bat-derived viruses were identified, representing an infection rate of nearly 5%. Evolutionary analyses revealed that all known hepaciviruses and pegiviruses, including those previously documented in humans and other primates, fall within the phylogenetic diversity of the bat-derived viruses described here. The prevalence, unprecedented viral biodiversity, phylogenetic divergence, and worldwide distribution of the bat-derived viruses suggest that bats are a major and ancient natural reservoir for both hepaciviruses and pegiviruses and provide insights into the evolutionary history of hepatitis C virus and the human GB viruses.

Bartonella spp. in Bats, Guatemala

To better understand the role of bats as reservoirs of Bartonella spp., we estimated Bartonella spp. prevalence and genetic diversity in bats in Guatemala during 2009. We found prevalence of 33% and identified 21 genetic variants of 13 phylogroups. Vampire bat–associated Bartonella spp. may cause undiagnosed illnesses in humans.

Discovery of diverse polyomaviruses in bats and the evolutionary history of the Polyomaviridae

Polyomaviruses (PyVs) have been identified in a wide range of avian and mammalian species. However, little is known about their occurrence, genetic diversity and evolutionary history in bats, even though bats are important reservoirs for many emerging viral pathogens. This study screened 380 specimens from 35 bat species from Kenya and Guatemala for the presence of PyVs by semi-nested pan-PyV PCR assays. PyV DNA was detected in 24 of the 380 bat specimens. Phylogenetic analysis revealed that the bat PyV sequences formed 12 distinct lineages. Full-genome sequences were obtained for seven representative lineages and possessed similar genomic features to known PyVs. Strikingly, this evolutionary analysis revealed that the bat PyVs were paraphyletic, suggestive of multiple species jumps between bats and other mammalian species, such that the theory of virus-host co-divergence for mammalian PyVs as a whole could be rejected. In addition, evidence was found for strong heterogeneity in evolutionary rate and potential recombination in a number of PyV complete genomes, which complicates both phylogenetic analysis and virus classification. In summary, this study revealed that bats are important reservoirs of PyVs and that these viruses have a complex evolutionary history.

Global Distribution of Bartonella Infections in Domestic Bovine and Characterization of Bartonella bovis Strains Using Multi-Locus Sequence Typing

Bartonella bovis is commonly detected in cattle. One B. bovis strain was recently isolated from a cow with endocarditis in the USA, suggesting its role as an animal pathogen. In the present study, we investigated bartonella infections in 893 cattle from five countries (Kenya, Thailand, Japan, Georgia, and Guatemala) and 103 water buffaloes from Thailand to compare the prevalence of the infection among different regions and different bovid hosts. We developed a multi-locus sequence typing (MLST) scheme based on nine loci (16S rRNA, gltA, ftsZ, groEL, nuoG, ribC, rpoB, ssrA, and ITS) to compare genetic divergence of B. bovis strains, including 26 representatives from the present study and two previously described reference strains (one from French cows and another from a cow with endocarditis in the USA). Bartonella bacteria were cultured in 6.8% (7/103) of water buffaloes from Thailand; all were B. bovis. The prevalence of bartonella infections in cattle varied tremendously across the investigated regions. In Japan, Kenya, and the Mestia district of Georgia, cattle were free from the infection; in Thailand, Guatemala, and the Dusheti and Marneuli districts of Georgia, cattle were infected with prevalences of 10–90%. The Bartonella isolates from cattle belonged to three species: B. bovis (n=165), B. chomelii (n=9), and B. schoenbuchensis (n=1), with the latter two species found in Georgia only. MLST analysis suggested genetic variations among the 28 analyzed B. bovis strains, which fall into 3 lineages (I, II, and III). Lineages I and II were found in cattle while lineage III was restricted to water buffaloes. The majority of strains (17/28), together with the strain causing endocarditis in a cow in the USA, belonged to lineage I. Further investigations are needed to determine whether B. bovis causes disease in bovids.

Bat rabies in Guatemala.

Rabies in bats is considered enzootic throughout the New World, but few comparative data are available for most countries in the region. As part of a larger pathogen detection program, enhanced bat rabies surveillance was conducted in Guatemala, between 2009 and 2011. A total of 672 bats of 31 species were sampled and tested for rabies. The prevalence of rabies virus (RABV) detection among all collected bats was low (0.3%). Viral antigens were detected and infectious virus was isolated from the brains of two common vampire bats (Desmodus rotundus). RABV was also isolated from oral swabs, lungs and kidneys of both bats, whereas viral RNA was detected in all of the tissues examined by hemi-nested RT-PCR except for the liver of one bat. Sequencing of the nucleoprotein gene showed that both viruses were 100% identical, whereas sequencing of the glycoprotein gene revealed one non-synonymous substitution (302T,S). The two vampire bat RABV isolates in this study were phylogenetically related to viruses associated with vampire bats in the eastern states of Mexico and El Salvador. Additionally, 7% of sera collected from 398 bats demonstrated RABV neutralizing antibody. The proportion of seropositive bats varied significantly across trophic guilds, suggestive of complex intraspecific compartmentalization of RABV perpetuation.

Viral Diversity, Prey Preference, and Bartonella Prevalence in Desmodus rotundus in Guatemala.

Certain bat species serve as natural reservoirs for pathogens in several key viral families including henipa-, lyssa-, corona-, and filoviruses, which may pose serious threats to human health. The Common Vampire Bat (Desmodus rotundus), due to its abundance, sanguivorous feeding habit involving humans and domestic animals, and highly social behavioral ecology, may have an unusually high potential for interspecies disease transmission. Previous studies have investigated rabies dynamics in D. rotundus, yet the diversity of other viruses, bacteria, and other microbes that these bats may carry remains largely unknown. We screened 396 blood, urine, saliva, and fecal samples from D. rotundus captured in Guatemala for 13 viral families and genera. Positive results were found for rhabdovirus, adenovirus, and herpesvirus assays. We also screened these samples for Bartonella spp. and found that 38% of individuals tested positive. To characterize potential for interspecies transmission associated with feeding behavior, we also analyzed cytochrome B sequences from fecal samples to identify prey species and found that domestic cattle (Bos taurus) made up the majority of blood meals. Our findings suggest that the risk of pathogen spillover from Desmodus rotundus, including between domestic animal species, is possible and warrants further investigation to characterize this microbial diversity and expand our understanding of foraging ecology in their populations.

Coexistence of Bartonella henselae and B. clarridgeiae in Populations of Cats and Their Fleas in Guatemala

ABSTRACT: Cats and their fleas collected in Guatemala were investigated for the presence of Bartonella infections. Bartonella bacteria were cultured from 8.2% (13/159) of cats, and all cultures were identified as B. henselae. Molecular analysis allowed detection of Bartonella DNA in 33.8% (48/142) of cats and in 22.4% (34/152) of cat fleas using gltA, nuoG, and 16S–23S internal transcribed spacer targets. Two Bartonella species, B. henselae and B. clarridgeiae, were identified in cats and cat fleas by molecular analysis, with B. henselae being more common than B. clarridgeiae in the cats (68.1%; 32/47 vs 31.9%; 15/47). The nuoG was found to be less sensitive for detecting B. clarridgeiae compared with other molecular targets and could detect only two of the 15 B. clarridgeiae-infected cats. No significant differences were observed for prevalence between male and female cats and between different age groups. No evident association was observed between the presence of Bartonella species in cats and in their fleas.

Antibody response of cattle to vaccination with commercial modified live rabies vaccines in Guatemala.

Vampire bat rabies is a public and animal health concern throughout Latin America. As part of an ecological study of vampire bat depredation on cattle in southern Guatemala, we conducted a vaccine seroconversion study among three dairy farms. The main objectives of this cross sectional and cohort study were to understand factors associated with bat bites among cattle, to determine whether unvaccinated cattle had evidence of rabies virus exposure and evaluate whether exposure was related to bat bite prevalence, and to assess whether cattle demonstrate adequate seroconversion to two commercial vaccines used in Guatemala. In 2012, baseline blood samples were collected immediately prior to intramuscular inoculation of cattle with one of two modified live rabies vaccines. Post vaccination blood samples were collected 13 and 393 days later. Sera were tested for rabies virus neutralizing antibodies (rVNA) by the rapid fluorescent focus inhibition test (RFFIT). Across two years of study, 36% (254/702) of inspected cattle presented gross evidence of vampire bat bites. Individual cattle with a bat bite in 2012 were more likely have a bat bite in 2013. Prior to vaccination, 12% (42/350) of cattle sera demonstrated rVNA, but bite status in 2012 was not associated with presence of rVNA. Vaccine brand was the only factor associated with adequate rVNA response of cattle by day 13. However, vaccine brand and rVNA status at day 13 were associated with an adequate rVNA titer on day 393, with animals demonstrating an adequate titer at day 13 more likely to have an adequate titer at day 393. Our findings support stable levels of vampire bat depredation and evidence of rVNA in unvaccinated cattle. Brand of vaccine may be an important consideration impacting adequate rVNA response and long-term maintenance of rVNA in cattle. Further, the results demonstrate that initial response to vaccination is associated with rVNA status over one year following vaccination.

Knowledge, attitudes and practices regarding rabies and exposure to bats in two rural communities in Guatemala

BackgroundRabies is a fatal encephalitis caused by rabies virus, of the genus Lyssavirus. The principal reservoir for rabies in Latin America is the common vampire bat (Desmodus rotundus), which feeds routinely on the blood of cattle, and when livestock are scarce, may prey on other mammals, including humans. Although rabies is endemic in common vampire bat populations in Guatemala, there is limited research on the extent of exposure to bats among human populations living near bat refuges.ResultsA random sample of 270 of 473 households (57%) in two communities located within 2 Km of a known bat roost was selected and one adult from each household was interviewed. Exposure to bats (bites, scratches or bare skin contact) was reported by 96 (6%) of the 1,721 residents among the selected households. Of those exposed, 40% received rabies post-exposure prophylaxis. Four percent of household respondents reported that they would seek rabies post exposure prophylaxis if they were bitten by a bat.ConclusionsThese findings demonstrate that exposure to bats in communities near bat roosts is common but recognition of the potential for rabies transmission from bats is low. There is a need for educational outreach to raise awareness of bat-associated rabies, prevent exposures to bats and ensure appropriate health-seeking behaviours for bat-inflicted wounds, particularly among communities living near bat roosts in Guatemala.