Infected Reservoir Hosts Research Articles

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.

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. IMPORTANCE Pathogenic 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.

Host adaptation drives genetic diversity in a vector-borne disease system.

The range of hosts a pathogen can infect is a key trait, influencing human disease risk and reservoir host infection dynamics. Borrelia burgdorferi sensu stricto (Bb), an emerging zoonotic pathogen, causes Lyme disease and is widely considered a host generalist, commonly infecting mammals and birds. Yet the extent of intraspecific variation in Bb host breadth, its role in determining host competence, and potential implications for human infection remain unclear. We conducted a long-term study of Bb diversity, defined by the polymorphic ospC locus, across white-footed mice, passerine birds, and tick vectors, leveraging long-read amplicon sequencing. Our results reveal strong variation in host breadth across Bb genotypes, exposing a spectrum of genotype-specific host-adapted phenotypes. We found support for multiple niche polymorphism, maintaining Bb diversity in nature and little evidence of temporal shifts in genotype dominance, as would be expected under negative frequency-dependent selection. Passerine birds support the circulation of several human-invasive strains (HISs) in the local tick population and harbor greater Bb genotypic diversity compared with white-footed mice. Mouse-adapted Bb genotypes exhibited longer persistence in individual mice compared with nonadapted genotypes. Genotype communities infecting individual mice preferentially became dominated by mouse-adapted genotypes over time. We posit that intraspecific variation in Bb host breadth and adaptation helps maintain overall species fitness in response to transmission by a generalist vector.

Low levels of genetic differentiation and structure in red fox populations in Eastern Canada and implications for Arctic fox rabies propagation potential.

Rabies is a lethal zoonosis present in most parts of the world which can be transmitted to humans through the bite from an infected mammalian reservoir host. The Arctic rabies virus variant (ARVV) persists mainly in populations of Arctic foxes (Vulpes lagopus), and to a lesser extent in red fox populations (Vulpes vulpes). Red foxes are thought to be responsible for sporadic southward movement waves of the ARVV outside the enzootic area of northern Canada. In this study, we wanted to investigate whether red foxes displayed notable levels of genetic structure across the Quebec-Labrador Peninsula, which includes portions of the provinces of Quebec and Newfoundland-Labrador in Canada, and is a region with a history of southward ARVV movement waves. We combined two datasets that were collected and genotyped using different protocols, totalling 675 red fox individuals across the whole region and genotyped across 13 microsatellite markers. We found two genetic clusters across the region, reflecting a latitudinal gradient, and characterized by low genetic differentiation. We also observed weak but significant isolation by distance, which seems to be marginally more important for females than for males. These findings suggest a general lack of resistance to movement in red fox populations across the Quebec-Labrador Peninsula, regardless of sex. Implications of these findings include additional support for the hypothesis of long-distance southward ARVV propagation through its red fox reservoir host.

A STUDY OF CLINICAL PROFILE OF LEPTOSPIROSIS IN A TERTIARY CARE HOSPITAL

Introduction: Leptospirosis is a zoonotic infection that can be lethal and is common in many tropical areas. It often spreads through huge epidemics following periods of high precipitation and floods. Exposure to infected reservoir host animals either directly or indirectly transmits infection. To study the clinical profile of leptospi Aim: rosis patients admitted in a tertiary care hospital. The present electronic record based retrospective study was co Methods nducted among eighty patients admitted with a diagnosis of leptospirosis at the Saveetha Medical College Hospital for the period of one year between January 2022 and December 2022. A total of 80 patients were included in the study Results . Among the study population 53.75% of the patients were males. The median age of the patients was 41.5 years. Most of the cases presented in the rainy season. In our study. most common symptom was fever (90%). Other symptoms were myalgia (87.5%), headache (41%), Abdominal pain (35%), Vomiting (25%), Loose stools (20%) and Dyspnea (10). Comorbidities in our study population include diabetes mellitus(n=8), systemic hypertension (n=6), coronary artery disease (n=1), hypothyroidism (n=2) and asthma (n=3). Complete hemogram revealed leucocytosis in 60% (n= 48) of the patients leucopenia in 2.5% (n=2), thrombocytopenia in 60% (n= 48) of the patients. Electrolyte abnormalities include hypokalemia (60%) , hyponatremia (40%) and hyperkalemia (n=2). Liver function tests (LFT) was deranged in 47.5% of the patients. Acute kidney injury was found in 27.5% patients (n=22) among which dialysis was needed for six patients. Liver was the most common organ affected followed by kidney. Bleeding manifestations occurred in 20% of the patients. Other complications include septic shock (18.75%) , acute respiratory distress syndrome (15%), encephalopathy (6.25%) and myocarditis (5%). Death occurred in 6.25% (n= 5) of the patients. Eventhough case fatal Conclusion: ity rate in leptospirosis is low, incidence of complications are higher. severe thrombocytopenia is associated with worse outcomes. Hypokalemia and hyponatremia are the most common electrolyte abnormalities. Liver and kidney are the most common organs affected. Incidence of cardiac and pulmonary manifestations leads to fatal outcomes.

The pathogenesis of zoonotic viral infections: Lessons learned by studying reservoir hosts.

Zoonotic viral infections that cause severe disease or even death in some people may be asymptomatic or mild in reservoir hosts. Comparison of the pathogenesis of these two host categories may potentially explain the difference in disease. However, infections in reservoir hosts are often neglected. Therefore, we compared the pathogenesis of rabies virus, macacine alphaherpesvirus, West Nile virus, Puumala orthohantavirus, monkeypox virus, Lassa mammarenavirus, H5N1 highly pathogenic avian influenza, Marburg virus, Nipah virus, Middle East respiratory syndrome, and simian/human immunodeficiency viruses in both humans and reservoir hosts. We showed that most aspects of the pathogeneses were remarkably similar. The remaining differences lead to the identification of tipping points in the pathogeneses that are important for explaining the disease outcome in severe human cases. Further elucidating these tipping points by studying zoonotic viral infections in their reservoir hosts may teach us how to reduce the severity of zoonotic viral diseases in humans.

Bartonella Prevalence and Genome Sequences in Rodents in Some Regions of Xinjiang, China.

In this study, we investigated Bartonella infection and its genetic diversity in rodents in Beitun, Xinjiang Uygur Autonomous Region, China. Small mammals were captured using snap traps at four sampling sites in 2018. Spleen and liver tissues were collected and cultured to isolate Bartonella strains. Whole-genome sequencing was performed on the strains identified as Bartonella by gltA gene PCR, and the average nucleotide identity (ANI) of the genomes was calculated by using FastANI v1.33. Phylogenetic trees were constructed for the samples positive for Bartonella spp. by the gltA PCR assay based on 1,290-bp gltA genes, 2,903-bp rpoB genes, and core-genome single nucleotide polymorphisms (SNPs). Among 66 rodents, 11 were positive for Bartonella, with an infection rate of 16.67%. The rodent infection rates in different tissues (χ2 = 2.133; P = 0.242), species (χ2 = 9.631; P = 0.141), and habitats (χ2 = 4.309; P = 0.312) did not show statistical differences. Bartonella spp. isolated from the rodents were phylogenetically divided into six clades (two different Bartonella species were detected in two rodents). By comparing phylogenetic trees based on gltA genes, rpoB genes, and SNPs, we found that the topological structures of several evolutionary trees are different. However, the Bartonella strains isolated in this study were clustered into six clusters in different phylogenetic trees. Broad distributions and high genetic diversity of Bartonella strains were observed among rodents in Beitun, Xinjiang. IMPORTANCE Rodent-borne Bartonella species have been associated with zoonotic diseases. Bartonella species such as Bartonella elizabethae, Bartonella grahamii, and Bartonella tribocorum can cause disease in humans. Humans can be infected by blood-sucking arthropods through the scratches and bites of an infected reservoir host or via contact with infectious rodents. Xinjiang is one of the provinces with the most abundant species of Bartonella in China, but there are few reports about the prevalence of Bartonella in the Beitun area. This research aims to investigate the occurrence and prevalence of Bartonella infection in rodents at these sampling sites and provide a basis for the prevention and control of rodent Bartonella species in Beitun and the surrounding areas of Xinjiang.

Potential Drivers for the Re-Emergence of Canine Leptospirosis in the United States and Canada.

Canine leptospirosis is an important zoonotic disease in many countries. This review examines potential drivers for increased diagnoses of canine leptospirosis in the United States and Canada, using the epidemiologic triad of agent-environment-host as a template. Leptospira spp. are classified into more than 250 serovars, but in many laboratories only 6 are routinely tested for in serologic agglutination tests of canine sera. Leptospiral infections in dogs may potentially go undetected with unemployed or currently employed diagnostic methods. Disease transmission from infected reservoir hosts usually occurs via urine-contaminated environmental sources such as water. Direct contact between infected and susceptible individuals, environmental factors such as climate changes in temperature and/or rainfall, and increasing number and urbanization of reservoir hosts may greatly increase dog exposure risks. A dog's lifestyle may influence exposure risk to leptospirosis, but vaccination based on proper identification of circulating serogroups dramatically reduces post-exposure infections. Regrettably, resistance to vaccination by veterinarians and dog owners leaves a large number of dogs at risk for this zoonotic disease.

A Borrelia burgdorferi outer surface protein C (OspC) genotyping method using Luminex technology.

Borrelia burgdorferi is an important tickborne human pathogen comprising several strains based on nucleotide sequence of the outer surface protein C (ospC) gene. Detection and characterization of different ospC genotypes is vital for research on B. burgdorferi and the risk it poses to humans. Here we present a novel, multiplex assay based on Luminex xMAP technology for the detection of B. burgdorferi ospC genotypes. The assay has five major steps: amplification of the ospC gene, hydrolyzation of surplus primers and nucleotides, incorporation of biotinylated nucleotides into the template DNA, hybridization to Luminex microspheres, and detection of fluorescent signals corresponding to each ospC genotype. We validated the protocol by comparing results obtained from our method against results from an established ospC genotyping method. This protocol can be used for the characterization of ospC genotypes in B. burgdorferi infected ticks, reservoir hosts, and/or clinical samples.

Factors affecting preventive behavior against leptospirosis among the population at risk in Si Sa Ket, Thailand

Leptospirosis is a major public health problem in Si Sa Ket, Thailand. Humans can become infected via direct contact with the urine of infected animal reservoir hosts or by indirect contact with contaminated soil and water in the environment. This study examined the factors affecting preventive behavior against leptospirosis among the population at risk in Si Sa Ket, Thailand. A cross-sectional questionnaire was conducted by a representative population survey using a four-stage stratified random sampling to select 350 respondents aged 18–65 years from the fifth districts with the highest morbidity rate in 2010–2019. Data were analyzed by descriptive statistics and stepwise multiple regression. The majority of the respondents were male (53.40%), aged 46–55 years (31.20%), and agricultural workers (76.00%). Their knowledge (M = 10.78, SD = 1.60), perceived severity (M = 2.91, SD = 0.60), perceived probability (M = 2.98, SD = 0.64), self-efficacy expectations (M = 3.18, SD = 0.63), responses-efficacy expectations (M = 3.16, SD = 0.71), social support (M = 3.19, SD = 0.52), and preventive behavior against leptospirosis (M = 3.29, SD = 0.49) were at moderate level. Significant factors affecting leptospirosis preventive behaviors were history of leptospirosis illness (β = 0.312), social support (β = 0.240), perceived probability (β = 0.238), household members with a history of leptospirosis illness (β = 0.158), perceived severity (β = 0.114), self-efficacy expectations (β = 0.094) and knowledge (β = 0.088) regarding leptospirosis. All of these factors could together predict the preventive behavior against leptospirosis up to 42.8% (Adjusted R2 = 0.428). Public health interventions should be strengthening people's perception and awareness regarding leptospirosis and the promotion of preventive health behavior to prevent potential outbreaks.

Prevalence of hookworm infections among stray dogs and molecular identification of hookworm species for the first time in Bangladesh.

Hookworms are the most common and voracious blood-sucking parasites of the small intestines of mammalian hosts such as dogs, cats, ruminants and humans. Canine hookworms are endemic in the Southeast Asian countries including Bangladesh. There is scarcity of information on the prevalence of hookworms of stray dogs in Bangladesh. The present study determined the prevalence of canine hookworms using fecal examination followed by morphometric and molecular identification. Fecal samples were collected from 320 stray dogs living in rural areas of Mymensingh district (Gauripur upazila, Mymensingh sadar upazila and Tarakanda upazila) and hookworm eggs were identified using the flotation techniques. The overall prevalence of hookworm was 79.1% through microscopic examination. Estimated fecal prevalence was higher in Gauripur upazila (89.7%) followed by Mymensingh sadar upazila (84.8%) and Tarakanda upazila (53.2%). Five hookworm species were identified based on the morphometric examination, namely, Ancylostoma caninum, Ancylostoma ceylanicum, Ancylostoma tubaeforme, Ancylostoma braziliense and Ancylostoma duodenale, respectively. Polymerase Chain Reaction (PCR) was performed with the genomic DNA by targeting the 5.8S rRNA (~ 404bp) and Cytochrome oxidase-1 (Cox 1, ~ 450bp) and confirmed the identification for the first time in Bangladesh. This study reveals that stray dogs may act as reservoir hosts of human hookworm infection. Further detail molecular study is warranted to explore the genetic diversity of hookworms that infect both dogs and human in Bangladesh.

Puumala Orthohantavirus Infection Does Not Affect the Trapping Success of Its Reservoir Host.

Pathogens might affect behavior of infected reservoir hosts and hence their trappability, which could bias population estimates of pathogen prevalence. In this study, we used snap-trapping data on Puumala orthohantavirus (PUUV)-infected (n = 1619) and noninfected (n = 6940) bank voles (Myodes glareolus) from five vole cycles, normally representing increase, peak, and decline phase, to evaluate if infection status affected trapping success. If PUUV infection, as previously suggested, increases activity and/or mobility, we would expect a higher proportion of infected than noninfected specimens in the first trapping night. However, the proportion of PUUV-infected voles did not differ across the three trapping nights. We conclude that PUUV infection did not affect trapping success, confirming snap trapping as an appropriate trapping method for studies on PUUV prevalence and likely other orthohantaviruses.

From bats to pangolins: new insights into species differences in the structure and function of the immune system.

Species differences in the structure and function of the immune system of laboratory animals are known to exist and have been reviewed extensively. However, the number and diversity of wild and exotic species, along with their associated viruses, that come into contact with humans has increased worldwide sometimes with lethal consequences. Far less is known about the immunobiology of these exotic and wild species. Data suggest that species differences of the mechanisms of inflammation, innate immunity and adaptive immunity are all involved in the establishment and maintenance of viral infections across reservoir hosts. The current review attempts to collect relevant data concerning the basics of innate and adaptive immune functions of exotic and wild species followed by identification of those differences that may play a role in the maintenance of viral infections in reservoir hosts.

Characteristics and Adverse Events of Patients for Whom Nifurtimox Was Released Through CDC-Sponsored Investigational New Drug Program for Treatment of Chagas Disease — United States, 2001–2021

Chagas disease, or American trypanosomiasis, is caused by the parasite Trypanosoma cruzi. Chagas disease is endemic in rural areas of Latin America, but T. cruzi, triatomine vectors, infected mammalian reservoir hosts, and rare cases of autochthonous vector borne transmission have been reported in the United States (1). Possible modes of transmission include the following: vector borne via skin or mucosal contact with feces of infected triatomine bugs, congenital, blood transfusion, organ transplantation, or laboratory accident. Chagas disease can be treated with benznidazole (commercially available since May 14, 2018) or nifurtimox (2). Before January 25, 2021, nifurtimox (Lampit) had been exclusively available through CDC under an Institutional Review Board-approved Investigational New Drug (IND) treatment protocol, at which time it became reasonably accessible to health care providers outside of the program. This report summarizes CDC Drug Service reports for selected characteristics of and adverse events reported by 336 patients for whom nifurtimox was requested under the CDC IND program during January 1, 2001-January 25, 2021. Of the 336 patients, 34.2% resided in California. Median age of patients was 37 years (range = 1-78 years). Most patients were aged ≥18 (91.8%; 305 of 332) and Hispanic (93.2%; 290 of 311). Among the patients with available information, 91.4% (222 of 243) reported an adverse event. Among those with information about the severity of their adverse events, 20.5% reported a severe event. On August 7, 2020, the Food and Drug Administration (FDA) announced approval of a nifurtimox product, Lampit (Bayer), for treatment of Chagas disease in patients aged <18 years weighing ≥5.5 lbs (≥2.5 kg). Lampit became commercially available during October 2020. Physicians should take frequency of adverse events into consideration when prescribing nifurtimox and counseling patients.

Gammaherpesvirus Infections in Cattle in Europe

The genus Macavirus, subfamily Gammaherpesvirinae, comprises ungulate viruses that infect domestic and wild ruminants and swine. They cause asymptomatic latent infections in reservoir hosts and malignant catarrhal fever in susceptible species. Lung, spleen, bronchial lymph node, and tongue were collected from 448 cattle (348 necropsied, 100 slaughtered) in Switzerland, United Kingdom, Finland, Belgium, and Germany to determine their infection with bovine herpesvirus-6 (BoHV-6) and gammaherpesviruses of other ruminants, i.e., ovine herpesvirus-1 and -2, caprine herpesvirus-2, and bison lymphotropic herpesvirus, using quantitative PCR. Only BoHV-6 was detected, with an overall frequency of 32%, ranging between 22% and 42% in the different countries. Infection was detected across all ages, from one day after birth, and was positively correlated with age. There was no evidence of an association with specific disease processes. In positive animals, BoHV-6 was detected in all organs with high frequency, consistently in the lungs or spleen. Viral loads varied substantially. In BoHV-6-positive gravid cows, organs of fetuses tested negative for infection, indicating that the virus is not vertically transmitted. Our results confirm previous data indicating that BoHV-6 is a commensal of domestic cattle not associated with disease processes and confirm that infections with other macaviruses are rare and sporadic.

Antigen-Specific Urinary Immunoglobulin in Reservoir Hosts of Leptospirosis.

Domestic and wildlife animal species act as reservoir hosts of leptospirosis, a global zoonotic disease affecting more than 1 million people annually and causing significant morbidity and mortality in domestic animals. In contrast to incidental hosts which present with an array of clinical manifestations, reservoir hosts are typically asymptomatic and can shed leptospires from chronically infected kidneys via urine for extended periods of time. Renal excretion of leptospires occurs despite evidence of a humoral and cellular immune response and is reflective of the unique biological equilibrium that exists between certain animal species and specific serovars of Leptospira. Here, we demonstrate that urinary excretion of leptospires is accompanied by the presence of antigen-specific urinary immunoglobulin. In rats experimentally infected with L. interrogans serovar Copenhageni using the intraperitoneal or conjunctival route of inoculation, urinary immunoglobulin (Ig) G specific for protein antigens was detectable within 1 week. Rat urinary IgG was not bound to urinary-derived leptospires. In cattle that were naturally exposed to, and infected with, L. borgpetersenii serovar Hardjo, urinary IgA specific for protein antigens was detected. Collectively, these results demonstrate that urinary excretion of immunoglobulin specific for leptospires is a hallmark of reservoir hosts of infection.

Application of CRISPR Interference (CRISPRi) for Gene Silencing in Pathogenic Species of &lt;em&gt;Leptospira&lt;/em&gt;

Leptospirosis is a global neglected zoonosis, responsible for at least 1 million cases per year and almost 60 thousand deaths. The disease is caused by pathogenic and virulent bacteria of the genus Leptospira, either by direct contact with the bacteria or indirectly by exposure to contaminated water or soil. Domestic and wild animals act as reservoir hosts of infection, shedding leptospires from colonized renal tubules of the kidney, via urine, into the environment. The generation of mutant strains of Leptospira is critical to evaluate and understand pathogenic mechanisms of infection. CRISPR interference (CRISPRi) has proven to be a straightforward, affordable, and specific tool for gene silencing in pathogenic Leptospira. Therefore, the methodological details of obtaining the plasmid constructs containing both dCas9 and guide RNA, delivery of plasmids to Leptospira by conjugation with the E. coli strain β2163, and transconjugant recovery and evaluation, will be described. In addition, the recently described Hornsby-Alt-Nally (HAN) media allows for the relatively rapid isolation and selection of mutant colonies on agar plates.

Application of CRISPR Interference (CRISPRi) for Gene Silencing in Pathogenic Species of Leptospira.

Leptospirosis is a global neglected zoonosis, responsible for at least 1 million cases per year and almost 60 thousand deaths. The disease is caused by pathogenic and virulent bacteria of the genus Leptospira, either by direct contact with the bacteria or indirectly by exposure to contaminated water or soil. Domestic and wild animals act as reservoir hosts of infection, shedding leptospires from colonized renal tubules of the kidney, via urine, into the environment. The generation of mutant strains of Leptospira is critical to evaluate and understand pathogenic mechanisms of infection. CRISPR interference (CRISPRi) has proven to be a straightforward, affordable, and specific tool for gene silencing in pathogenic Leptospira. Therefore, the methodological details of obtaining the plasmid constructs containing both dCas9 and guide RNA, delivery of plasmids to Leptospira by conjugation with the E. coli strain β2163, and transconjugant recovery and evaluation, will be described. In addition, the recently described Hornsby-Alt-Nally (HAN) media allows for the relatively rapid isolation and selection of mutant colonies on agar plates.

From Protein to Pandemic: The Transdisciplinary Approach Needed to Prevent Spillover and the Next Pandemic.

Pandemics are a consequence of a series of processes that span scales from viral biology at 10−9 m to global transmission at 106 m. The pathogen passes from one host species to another through a sequence of events that starts with an infected reservoir host and entails interspecific contact, innate immune responses, receptor protein structure within the potential host, and the global spread of the novel pathogen through the naive host population. Each event presents a potential barrier to the onward passage of the virus and should be characterized with an integrated transdisciplinary approach. Epidemic control is based on the prevention of exposure, infection, and disease. However, the ultimate pandemic prevention is prevention of the spillover event itself. Here, we focus on the potential for preventing the spillover of henipaviruses, a group of viruses derived from bats that frequently cross species barriers, incur high human mortality, and are transmitted among humans via stuttering chains. We outline the transdisciplinary approach needed to prevent the spillover process and, therefore, future pandemics.

Camelid Inoculation With Middle East Respiratory Syndrome Coronavirus: Experimental Models of Reservoir Host Infection.

Within the past two decades, three zoonotic betacoronaviruses have been associated with outbreaks causing severe respiratory disease in humans. Of these, Middle East respiratory s yndrome coronavirus (MERS-CoV) is the only zoonotic coronavirus that is known to consistently result in frequent zoonotic spillover events from the proximate reservoir host—the dromedary camel. A comprehensive understanding of infection in dromedaries is critical to informing public health recommendations and implementing intervention strategies to mitigate spillover events. Experimental models of reservoir disease are absolutely critical in understanding the pathogenesis and transmission, and are key to testing potential dromedary vaccines against MERS-CoV. In this review, we describe experimental infections of dromedary camels as well as additional camelid models used to further understand the camel’s role in MERS-CoV spillover to humans.