Identification of equine mares as reservoir hosts for pathogenic species of Leptospira.

Equine leptospirosis can result in abortion, stillbirth, neonatal death, placentitis, and uveitis. Horses can also act as subclinical reservoir hosts of infection, which are characterized as asymptomatic carriers that persistently excrete leptospires and transmit disease. In this study, PCR and culture were used to assess urinary shedding of pathogenic Leptospira from 37 asymptomatic mares. Three asymptomatic mares, designated as H2, H8, and H9, were PCR-positive for lipL32, a gene specific for pathogenic species of Leptospira. One asymptomatic mare, H9, was culture-positive, and the recovered isolate was classified as L. kirschneri serogroup Australis serovar Rushan. DNA capture and enrichment of Leptospira genomic DNA from PCR-positive, culture-negative samples determined that asymptomatic mare H8 was also shedding L. kirschneri serogroup Australis, whereas asymptomatic mare H2 was shedding L. interrogans serogroup Icterohaemorrhagiae. Sera from all asymptomatic mares were tested by the microscopic agglutination test (MAT) and 35 of 37 (94.6%) were seropositive with titers ranging from 1:100 to 1:3200. In contrast to asymptomatic mares, mare H44 presented with acute spontaneous abortion and a serum MAT titer of 1:102,400 to L. interrogans serogroup Pomona serovar Pomona. Comparison of L. kirschneri serogroup Australis strain H9 with that of L. interrogans serogroup Pomona strain H44 in the hamster model of leptospirosis corroborated differences in virulence of strains. Since lipopolysaccharide (LPS) is a protective antigen in bacterin vaccines, the LPS of strain H9 (associated with subclinical carriage) was compared with strain H44 (associated with spontaneous abortion). This revealed different LPS profiles and immunoreactivity with reference antisera. It is essential to know what species and serovars of Leptospira are circulating in equine populations to design efficacious vaccines and diagnostic tests. Our results demonstrate that horses in the US can act as reservoir hosts of leptospirosis and shed diverse pathogenic Leptospira species via urine. This report also details the detection of L. kirschneri serogroup Australis serovar Rushan, a species and serotype of Leptospira, not previously reported in the US.

Gapless assembly of Babesia bovis NVSL348.

We are reporting a Babesia bovis genome containing four nuclear chromosomes, a mitochondrial genome, and an apicoplast from reference isolate NVSL348. This report includes a gapless assembly consisting of all six genetic molecules.

Concurrent colonization of rodent kidneys with multiple species and serogroups of pathogenic Leptospira.

Rodents are important reservoir hosts of pathogenic leptospires in the US Virgin Islands. Our previous work determined that trapped rodents were colonized with Leptospira borgpetersenii serogroup Ballum (n = 48) and/or Leptospira kirschneri serogroup Icterohaemorrhagiae (n = 3). In addition, nine rodents appeared to be colonized with a mixed population comprising more than one species/serogroup. The aim of this study was to validate this finding by characterizing clonal isolates derived from cultures of mixed species. Cultures of presumptive mixed species (designated LR1, LR5, LR37, LR57, LR60, LR61, LR68, LR70, and LR72) were propagated in different media including Hornsby-Alt-Nally (HAN) media, incubated at both 29℃ and 37℃, and T80/40/LH incubated at 29℃. Polyclonal reference antisera specific for serogroup Ballum and Icterohaemorrhagiae were used to enrich for different serogroups followed by subculture on agar plates. Individual colonies were then selected for genotyping and serotyping. Of the nine cultures of mixed species/serogroups, a single clonal isolate was separated in five of them: L. borgpetersenii serogroup Ballum in LR1, LR5, and LR37, and L. kirschneri serogroup Icterohaemorrhagiae in LR60 and LR72. In four of the cultures with mixed species (LR57, LR61, LR68, and LR70), clonal isolates of both L. borgpetersenii serogroup Ballum and L. kirschneri serogroup Icterohaemorrhagiae were recovered. Our results definitively establish that rodents can be colonized with more than one species/serogroup of Leptospira concurrently. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.IMPORTANCEPathogenic Leptospira, the causative agent of human and animal leptospirosis, comprise a diverse genus of species/serogroups which are inherently difficult to isolate from mammalian hosts due to fastidious growth requirements. Molecular evidence has indicated that reservoir hosts of Leptospira may shed multiple species concurrently. However, evidence of this phenomena by culture has been lacking. Culture is definitive and is essential for comprehensive characterization of recovered isolates by high-resolution genome sequencing and serotyping. In this work, a protocol using recently developed novel media formulations, in conjunction with reference antisera, was developed and validated to demonstrate the recovery of multiple species/serogroups of pathogenic Leptospira from the same host. The identification and characterization of multiple species/serogroups of Leptospira from individual reservoir hosts of infection are essential to understand the epidemiology and transmission of disease to both human and domestic animal populations.

Complete genome sequence of Candidatus Mycobacterium wuenschmannii, a nontuberculous mycobacterium isolated from a captive population of Amazon milk frogs.

A slow growing species of nontuberculous mycobacteria (NTM) was isolated from the liver of an Amazon milk frog. The complete genome of this isolate comprises 5,102,433 bp, exhibiting 66.86% GC content, 4,940 protein-coding sequences, 52 predicted RNA genes, and 39 repeat regions.

Diagnostic Evaluation of the IS1081-Targeted Real-Time PCR for Detection of Mycobacterium bovis DNA in Bovine Milk Samples.

The ability of Mycobacterium bovis (M. bovis) to survive in bovine milk has emerged as a serious public health concern. The first objective of this study was to evaluate the diagnostic utility of IS1081-targeted real-time PCR for the detection of M. bovis DNA in different fractions of bovine milk. In a model study, bovine milk samples were spiked with serially diluted M. bovis BCG to investigate the detection limit of M. bovis DNA in whole milk and milk fractions (cream, pellet, and pellet + cream combined) using IS1081 real-time PCR. The assay was then used to detect M. bovis DNA in whole milk and milk fractions from naturally infected animals. The results showed that the IS1081 real-time PCR was more sensitive when detecting M. bovis DNA in the cream layer alone and cream + pellet combined compared to whole milk or the pellet alone. While PCR-based diagnostic assays for the detection of M. bovis in milk samples provide a quicker diagnostic tool for bovine tuberculosis, safe processing, and handling of M. bovis-infected milk samples remain a challenge and pose a human health risk. PrimeStore Molecular Transport Medium (MTM) has been shown to rapidly inactivate infected specimens while preserving nucleic acid for subsequent Molecular analysis. Therefore, the secondary objective of this study was to evaluate the ability of MTM to inactivate M. bovis BCG in spiked milk samples as well as its ability to preserve BCG DNA for the PCR assay. The results showed that MTM can successfully inactivate BCG alone or in spiked milk samples while preserving DNA for the PCR assay. The CT values of M. bovis BCG alone and spiked milk samples aliquoted in MTM and without MTM were similar at various dilutions. Taken together, our results indicate that using DNA extracted from the milk cream fraction alone or combined milk cream and pellet improved the recovery rate of M. bovis DNA in bovine milk samples. MTM has the potential to provide a safe and rapid sample processing tool for M. bovis inactivation in milk samples and preserve DNA for molecular diagnostics.

Whole genome sequencing of Mycobacterium bovis directly from clinical tissue samples without culture.

Advancement in next generation sequencing offers the possibility of routine use of whole genome sequencing (WGS) for Mycobacterium bovis (M. bovis) genomes in clinical reference laboratories. To date, the M. bovis genome could only be sequenced if the mycobacteria were cultured from tissue. This requirement for culture has been due to the overwhelmingly large amount of host DNA present when DNA is prepared directly from a granuloma. To overcome this formidable hurdle, we evaluated the usefulness of an RNA-based targeted enrichment method to sequence M. bovis DNA directly from tissue samples without culture. Initial spiking experiments for method development were established by spiking DNA extracted from tissue samples with serially diluted M. bovis BCG DNA at the following concentration range: 0.1 ng/µl to 0.1 pg/µl (10-1 to 10-4). Library preparation, hybridization and enrichment was performed using SureSelect custom capture library RNA baits and the SureSelect XT HS2 target enrichment system for Illumina paired-end sequencing. The method validation was then assessed using direct WGS of M. bovis DNA extracted from tissue samples from naturally (n = 6) and experimentally (n = 6) infected animals with variable Ct values. Direct WGS of spiked DNA samples achieved 99.1% mean genome coverage (mean depth of coverage: 108×) and 98.8% mean genome coverage (mean depth of coverage: 26.4×) for tissue samples spiked with BCG DNA at 10-1 (mean Ct value: 20.3) and 10-2 (mean Ct value: 23.4), respectively. The M. bovis genome from the experimentally and naturally infected tissue samples was successfully sequenced with a mean genome coverage of 99.56% and depth of genome coverage ranging from 9.2× to 72.1×. The spoligoyping and M. bovis group assignment derived from sequencing DNA directly from the infected tissue samples matched that of the cultured isolates from the same sample. Our results show that direct sequencing of M. bovis DNA from tissue samples has the potential to provide accurate sequencing of M. bovis genomes significantly faster than WGS from cultures in research and diagnostic settings.

National Prevalence of Caprine Prion Protein Genetic Variability at Codons 146, 211, and 222 in Goat Herds in the United States.

Scrapie is a neurodegenerative disease that impacts sheep and goats, characterized by gradual and progressive changes in neurological function. Recent research shows that the scrapie incubation period is significantly influenced by specific variations in amino acids within the prion protein gene (PRNP). The objective of this study was to estimate the national prevalence of caprine PRNP genetic variability at codons 146, 211, and 222 in goat populations across the United States. A total of 3052 blood, ear tissue, and brain tissue samples were collected from goats from 50 states. The participating states were categorized into four Veterinary Service (VS) district regions. The samples underwent DNA extraction, and the PRNP variants corresponding to codons 146, 211, and 222 were amplified and sequenced. The analysis of PRNP variants, when compared to the PRNP reference sequence, revealed seven alleles in twelve genotypes. The homozygous 146NN, 211RR, and 222QQ alleles, which have been linked to an increased risk of scrapie, were found to be the most prevalent among all the goats. The heterozygous 222QK, 211RQ, 146SD, 146ND, and 146NS alleles and the homozygous 222KK, 146SS, and 146DD alleles, known to be associated with reduced scrapie susceptibility and a prolonged incubation period after experimental challenge, were found in 1.098% (222QK), 2.33% (211RQ), 0.58% (146SD), 3.13% (146ND), 20.68% (146NS), 0.005% (222KK), 3.31% (146SS), and 0.67% (146DD) of goats, respectively. The 222QK allele was found most frequently in goats tested from the east (VS District 1, 1.59%) and southwest (VS District 4, 1.08%) regions, whereas the 211RQ allele was found most often in goats tested from the Midwest (VS District 2, 8.03%) and east (VS District 1, 6.53%) regions. The 146NS allele was found most frequently in goats tested from the northwest (VS District 3, 29.02%) and southwest (VS District 4, 20.69%) regions. Our results showed that the prevalence of less susceptible genotypes at PRNP codon 146 may be sufficient to use genetic susceptibility testing in some herds. This may reduce the number of goats removed as part of a herd clean-up plan and may promote the selective breeding goats for less susceptible alleles in high-risk herds at the national level.

Leptospira borgpetersenii serovar Hardjo and Leptospira santarosai serogroup Pyrogenes isolated from bovine dairy herds in Puerto Rico.

Leptospirosis is one of the most common zoonotic diseases in the world and endemic in the Caribbean Islands. Bovine leptospirosis is an important reproductive disease. Globally, cattle are recognized as a reservoir host for L. borgpetersenii serovar Hardjo, which is transmitted via urine, semen, and uterine discharges, and can result in abortion and poor reproductive performance. The dairy industry in Puerto Rico comprises up to 25% of agriculture-related income and is historically the most financially important agricultural commodity on the island. In this study, we report the isolation of two different pathogenic Leptospira species, from two different serogroups, from urine samples collected from dairy cows in Puerto Rico: L. borgpetersenii serogroup Sejroe serovar Hardjo and L. santarosai serogroup Pyrogenes. Recovered isolates were classified using whole-genome sequencing, serotyping with reference antisera and monoclonal antibodies, and immunoblotting. These results demonstrate that dairy herds in Puerto Rico can be concurrently infected with more than one species and serovar of Leptospira, and that bacterin vaccines and serologic diagnostics should account for this when applying intervention and diagnostic strategies.

Bovine Leptospirosis Due to Persistent Renal Carriage of Leptospira borgpetersenii Serovar Tarassovi.

Leptospirosis is a global zoonotic disease that causes significant morbidity and mortality in human and animal populations. Leptospira interrogans is a leading cause of human disease, and L. borgpetersenii is a leading cause of animal disease. Cattle are reservoir hosts of L. borgpetersenii serovar Hardjo, which is transmitted via urine, semen, and uterine discharges resulting in abortion and poor reproductive performance. Bovine bacterin vaccines can only protect against those serovars included in vaccine formulations and typically include serovar Hardjo among others. Genotyping and serotyping represent two different and unique methods for classifying leptospires that do not always correlate well; comprehensive characterization using either method requires recovery of isolates from infected animals. In this study, we report for the first time, isolation of L. borgpetersenii serovar Tarassovi from the urine of a dairy cow in the U.S. The classification of the isolate, designated strain MN900, was confirmed by whole-genome sequencing, serotyping with reference antisera and monoclonal antibodies, Matrix Assisted Laser Desorption/Ionization (MALDI), and immunoblotting with reference antisera. Strain MN900 was excreted in urine samples for 18 weeks even as the cow was seronegative for serovar Tarassovi. Strain MN900 has an unusual morphology since it is not as motile as other leptospires and lacks hooked ends. Serovar Tarassovi is not included in U.S. bacterin vaccines. These results demonstrate the importance of culture and concomitant genotyping and serotyping to accurately classify leptospires, and as required to design efficacious vaccine and diagnostic strategies to not only limit animal disease but reduce zoonotic risk.

Draft Genome Sequence of the Mycobacterium tuberculosis Complex Pathogen M. mungi, Identified in a Banded Mongoose (Mungos mungo) in Northern Botswana.

Mycobacterium mungi, a Mycobacterium tuberculosis complex pathogen, has emerged in banded mongoose in northern Botswana and Northwest Zimbabwe. The pathogen is transmitted through infected secretions used in olfactory communication behavior (K. A. Alexander, C. E. Sanderson, M. H. Larsen, S. Robbe-Austerman, M. C. Williams, and M. V. Palmer, mBio 7(3):e00281-16, 2016, http://dx.doi.org/10.1128/mBio.00281-16). We announce here the draft genome sequence of this emerging pathogen.

Association of Smoking and CFH and ARMS2 Risk Variants With Younger Age at Onset of Neovascular Age-Related Macular Degeneration.

IMPORTANCE: The age at which the first signs of age-related macular degeneration (AMD) manifest is variable. Better insight into factors that influence disease onset has direct implications for preventive measures and patient counseling. OBJECTIVE: To identify risk factors for an earlier age at onset of neovascular AMD. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study, including patient data from the European Genetic Database collected between April 2006 and July 2010. All patients had at least 1 documented visit to the outpatient AMD clinic of the Radboud University Medical Center, Nijmegen, the Netherlands, a tertiary referral center for retinal disorders. In total, 275 patients with a known age at onset of neovascular AMD and a genetic risk analysis were included. MAIN OUTCOMES AND MEASURES: Effects of several genetic, sociodemographic, behavioral, and ocular factors on the age at onset of neovascular AMD. The mean differences in the age at onset were determined using general linear models with the age at onset as the dependent variable. RESULTS: Past smokers and current smokers developed neovascular AMD on average 4.9 (95% CI, 3.0-6.8) and 7.7 (95% CI, 5.3-10.0) years earlier, respectively, than never smokers (P < .001 for both). Compared with the reference group, the age at onset was 5.2 (95% CI, 2.8-7.7) years earlier for homozygous carriers of the A69S risk allele in the age-related maculopathy susceptibility 2 (ARMS2) gene (P < .001). Homozygous carriers of the Y402H risk variant in the complement factor H (CFH) gene developed neovascular AMD 2.8 (95% CI, 0.5-5.0) years earlier (P = .02). Patients carrying 4 risk alleles in CFH and ARMS2 developed neovascular AMD 12.2 (95% CI, 6.2-18.3) years earlier than patients with zero risk alleles (P < .001). CONCLUSIONS AND RELEVANCE: Genetic and environmental risk factors influence the age at onset of neovascular AMD. Individuals at risk could be identified at an early age if and when preventive or therapeutic options become available. Insight into individual risk profiles might influence patients' consideration of interventions to increase their chance of avoiding vision loss from AMD.

Identification of Mycobacterium spp. of veterinary importance using rpoB gene sequencing.

BACKGROUND: Studies conducted on Mycobacterium spp. isolated from human patients indicate that sequencing of a 711 bp portion of the rpoB gene can be useful in assigning a species identity, particularly for members of the Mycobacterium avium complex (MAC). Given that MAC are important pathogens in livestock, companion animals, and zoo/exotic animals, we were interested in evaluating the use of rpoB sequencing for identification of Mycobacterium isolates of veterinary origin. RESULTS: A total of 386 isolates, collected over 2008 - June 2011 from 378 animals (amphibians, reptiles, birds, and mammals) underwent PCR and sequencing of a ~ 711 bp portion of the rpoB gene; 310 isolates (80%) were identified to the species level based on similarity at ≥ 98% with a reference sequence. The remaining 76 isolates (20%) displayed < 98% similarity with reference sequences and were assigned to a clade based on their location in a neighbor-joining tree containing reference sequences. For a subset of 236 isolates that received both 16S rRNA and rpoB sequencing, 167 (70%) displayed a similar species/clade assignation for both sequencing methods. For the remaining 69 isolates, species/clade identities were different with each sequencing method. Mycobacterium avium subsp. hominissuis was the species most frequently isolated from specimens from pigs, cervids, companion animals, cattle, and exotic/zoo animals. CONCLUSIONS: rpoB sequencing proved useful in identifying Mycobacterium isolates of veterinary origin to clade, species, or subspecies levels, particularly for assemblages (such as the MAC) where 16S rRNA sequencing alone is not adequate to demarcate these taxa. rpoB sequencing can represent a cost-effective identification tool suitable for routine use in the veterinary diagnostic laboratory.