Equi Infection Research Articles

In silico approaches for predicting natural compounds with therapeutic potential and vaccine candidates against Streptococcus equi

Equine strangles is a prevalent disease that affects the upper respiratory in horses and is caused by the Gram-positive bacterium Streptococcus equi. In addition to strangles, other clinical conditions are caused by the two S. equi subspecies, equi and zooepidemicus, which present relevant zoonotic potential. Treatment of infections caused by S. equi has become challenging due to the worldwide spreading of infected horses and the unavailability of effective therapeutics and vaccines. Penicillin treatment is often recommended, but multidrug resistance issues arised. We explored the whole genome sequence of 18 S. equi isolates to identify candidate proteins to be targeted by natural drug-like compounds or explored as immunogens. We considered only proteins shared among the sequenced strains of subspecies equi and zooepidemicus, absent in the equine host and predicted to be essential and involved in virulence. Of these, 4 proteins with cytoplasmic subcellular location were selected for molecular docking with a library of 5008 compounds, while 6 proteins were proposed as prominent immunogens against S. equi due to their probabilities of behaving as adhesins. The molecular docking analyses revealed the best ten ligands for each of the 4 drug target candidates, and they were ranked according to their binding affinities and the number of hydrogen bonds for complex stability. Finally, the natural 5-ring compound C25H20F3N5O3 excelled in molecular dynamics simulations for the increased stability in the interaction with UDP-N-acetylenolpyruvoylglucosamine reductase (MurB). This research paves the way to developing new therapeutics to minimize the impacts caused by S. equi infections. Communicated by Ramaswamy H. Sarma

The impact of age on vitamin D receptor expression, vitamin D metabolism and cytokine production in ex vivo Rhodococcus equi infection of equine alveolar macrophages

Rhodococcus equi (R. equi), a pneumonia-causing intracellular bacterium, results in significant morbidity and mortality in young foals, while healthy adult horses rarely develop disease. Survival and replication within alveolar macrophages (AMφ) are the hallmarks of R. equi’s pathogenicity. The vitamin D receptor (VDR) and its ligand, the active vitamin D metabolite 1,25(OH)2D, are important in immune responses to intracellular bacteria. The vitamin D/VDR pathway regulates the downstream production of cytokines in infected human AMφ. The immunomodulatory role of the vitamin D/VDR pathway in equine leukocytes is unknown. The objective of the current study was to determine the impact of R. equi infection and age on synthesis of 1,25(OH)2D, VDR expression, and cytokine production in an ex vivo model of R. equi infection in equine AMφ. AMφ were collected from ten healthy foals at 2-, 4- and 8-weeks old and from nine healthy adult horses once via bronchoalveolar lavage. AMφ were mock infected (CONTROL) or infected with a virulent laboratory strain of R. equi for 7 days (INFECTED). VDR expression was determined via RT-qPCR from cell lysates. 1,25(OH)2D and cytokines were measured in cell supernatant by immunoassays. VDR expression was impacted by age (P = 0.001) with higher expression in AMφ from 8-week-old foals than from 2-week-old foals and adults. There was no significant effect of infection in foal AMφ, but in adults, relative VDR expression was significantly lower in INFECTED AMφ compared to CONTROL AMφ (P = 0.002). There was no effect of age or infection on 1,25(OH)2D concentration (P > 0.37). Mean TNFα production was significantly higher from INFECTED compared to CONTROL AMφ from 4- and 8-week-old foals and adults (P < 0.005). Mean IFNγ production was significantly higher from AMφ from foals at 8-weeks-old compared to 2-weeks-old (P = 0.013) and higher from INFECTED AMφ than from CONTROL AMφ in foals at 4-weeks-old and in adults (P < 0.027). The proportion of samples producing IL-1β and IL-10 was also significantly higher from INFECTED compared to CONTROL AMφ isolated from 4-week-old foals (P < 0.008). Similarly, in adult samples, IL-17 was produced from a greater proportion of INFECTED compared to CONTROL samples (P = 0.031). These data document age-associated changes in VDR expression and cytokine production in equine AMφ in response to R. equi infection. This preliminary investigation supports the need for further research to fully elucidate if the vitamin D pathway has an immunomodulatory role in the horse.

Prevalência do vírus da anemia infecciosa equina em cavalos e burros, determinada por comparação de ELISA e AGID, no México

ABSTRACT From February to December 2021, 960 serum samples from different climate regions in two Mexican states were analyzed for antibodies against EIAV using competitive enzyme-linked immunosorbent assay (cELISA) and agar gel immunodiffusion (AGID) tests. The overall seroprevalence of EIAV infection in equids determined by ELISA and AGID tests was 19.69% and 17.60%, respectively. The highest rate of seropositivity was observed in the state of Veracruz (23.67%, using AGID test), and the lowest rate was found in the state of Puebla (13.12%, using cELISA test). In total, 17.45% (85/487, using AGID test) and 15.40% (75/487, using cELISA test) of horses were positive for EIAV infection. Donkeys showed a prevalence of 19.87% (94/473) in cELISA and 21.99% (104/476) in AGID. The cELISA was compared with AGID as the gold standard test. The diagnostic sensitivity for horses and donkeys was 90.4% and 92.2%, and the specificity was 97.5% and 97.3%, respectively, with an almost perfect degree of agreement (kappa values of 0.871 and 0.888). Therefore, the overall seroprevalence rate of EIAV infection in equines in the sampled states of Puebla and Veracruz was 19.3%, with 91.4% sensitivity, 97.4% specificity, and an agreement of 96.25%, indicating almost perfect agreement (kappa = 0.880).

Molecular Detection of Equine Herpesviruses from Field Outbreaks in Donkeys in Northwest Amhara Region, Ethiopia.

Equine herpesviruses pose a threat to equine health and potentially cause substantial economic losses to the global equine industry. EHV outbreaks have been reported in various parts of Ethiopia and the Amhara region specifically. This study aimed to detect EHVs from suspected outbreak cases in selected districts of the Northwest Amhara region. A cross-sectional study was performed from January 2022 to July 2022 to detect EHVs from suspected outbreak cases. Clinical observation was conducted for the presumptive identification of equine herpesvirus infection, and nasopharyngeal swab samples were collected for molecular detection of the viruses for confirmation. Out of 463 donkeys observed, 23 donkeys showed clinical signs suggestive of equine herpesvirus infection. Samples from 10 suspected donkeys were further subjected to polymerase chain reaction (PCR) test, amplifying ORF30 for EHV-1 and gB for EHV-2 and EHV-5. Among the 10 donkeys tested, seven (n = 7) were positive for EHV-5. All ten (n = 10) tested donkeys were negative for EHV-1 and EHV-2. EHV-5 was detected in animals with nervous signs, respiratory signs, a combination of nervous and respiratory signs, and a combination of abortion, respiratory, and nervous signs. Generally, only EHV-5 was identified from the outbreak, and more detailed epidemiological/molecular studies should be performed to better understand its dynamics and inform preventive measures.

Determination of risk factors associated with R. equi infection in foals

Determination of risk factors associated with R. equi infection in foals

Герпесвирусная инфекция у лошадей в Казахстане

For horse breeding in many countries of the world, herpesvirus infections are a constant threat, primarily equine herpesvirus infection (rhinopneumonia–viral abortion of horses). In the course of the work, an epizootological analysis of the situation on the territory of the country and the world over the past 10 years – from 2014 to 2023, is carried out. As a result of the conducted research, the epizootological characteristics of the territory of the Republic of Kazakhstan for the last 10 years on horse rhinopneumonia were determined, zoning and regionalization of the territory of the Republic of Kazakhstan were carried out according to the degree of intensity of the epizootic situation on horse rhinopneumonia. The spread of rhinopneumonia among horses in various regions, as well as the identification of factors contributing to its transmission

Viremia and nasal shedding for the diagnosis of equine herpesvirus-1 infection in domesticated horses.

Equine herpesvirus type 1 (EHV-1) infection is associated with upper respiratory disease, EHM, abortions, and neonatal death. Are nasal secretions a more sensitive biological sample compared to blood for the detection of EHV-1 infection? How long is EHV-1 detectable after primary infection by PCR? MedLine and Web of Science searches identified original peer-reviewed reports evaluating nasal shedding and viremia using virus isolation methods or PCR published in English before October 9, 2023. Sixty experimental and 20 observational studies met inclusion criteria. EHV-1 detection frequency by qPCR in nasal secretions and blood from naturally-infected horses with fever and respiratory signs were 15% and 9%, respectively; qPCR detection rates in nasal secretions and blood from horses with suspected EHM were 94% and 70%, respectively. In experimental studies the sensitivity of qPCR matched or exceeded that seen for virus isolation from either nasal secretions or blood. Detection of nasal shedding typically occurred within 2 days after EHV-1 inoculation with a detection period of 3 to 7 days. Viremia lasted 2 to 7 days and was usually detected ≥1 days after positive identification of EHV-1 in nasal secretions. Nasal shedding and viremia decreased over time and remained detectable in some horses for several weeks after inoculation. Under experimental conditions, blood and nasal secretions have similar sensitivity for the detection of EHV-1 when horses are sampled on multiple consecutive days. In contrast, in observational studies detection of EHV-1 in nasal secretions was consistently more successful.

Cross-Sectional Survey of Horse Owners to Assess Their Knowledge and Use of Biosecurity Practices for Equine Infectious Diseases in the United States.

Horses are transported in the United States more than any other livestock species and co-mingle at various events; therefore, they are considered to be at an increased risk for infectious disease transmission. The fragmented movement of horses combined with numerous sites of co-mingling makes tracing the potential spread of a disease outbreak a necessary part of an infection control plan, both locally and nationally. The cross-movement of personnel with horses and the persistence of endemic diseases make biosecurity implementation an ongoing challenge. Although many of the risks for infection are known, there is limited documentation about the usefulness of prospective control measures. The objective of this survey was to determine horse owners' understanding and knowledge of biosecurity practices for preventing infectious diseases in the United States. Questions covered owner demographic information, including horse use which was divided into 10 categories as follows: Pleasure/Trail Riding, Lessons/School, Western Show, English Show, Breeding, Farm/Ranch, Retired, Racing, Driving and Other. The survey was distributed by sending requests to a list of horse owner organizations, which then sent emails to their members. The email request described the survey and provided a website link to start the survey. A total of 2413 responses were collected. Analysis of the results included cross-tabulation to identify significant differences in biosecurity knowledge and awareness by horse use. Significant differences by horse use were identified for vaccination, biosecurity planning, use of isolation, disease risk, monitoring for diseases, co-mingling of horses, sanitation, medical decision making and health record requirements for horse events. In summary, the results suggest that most owners are not highly concerned about the risk of disease or the use of biosecurity. There are several biosecurity applications and techniques which can be increased and will benefit horse health and welfare. These include reliance on temperature monitoring, isolation of new horses at facilities, risks of horse mingling, entry requirements such as vaccination and health certificates at events, and an emphasis on having biosecurity plans for facilities and events where horses co-mingle. The information from this study will be used to create tools and information that horse owners and veterinarians can use to implement appropriate biosecurity practices for different types of horse uses and events.

Serological Evidence of Hepatitis E Virus Infection in Brazilian Equines.

Hepatitis E virus (HEV) infection has been demonstrated in various animal species; those recognized as potential zoonotic reservoirs pose a considerable risk to public health. In Brazil, HEV-3 is the only genotype identified in humans and swine nationwide, in a colony-breeding cynomolgus monkey and, recently, in bovines and capybara. There is no information regarding HEV exposure in the equine population in Brazil. This study aimed to investigate anti-HEV antibodies and viral RNA in serum samples from horses slaughtered for meat export and those bred for sport/reproduction purposes. We used a commercially available ELISA kit modified to detect species-specific anti-HEV, using an anti-horse IgG-peroxidase conjugate and evaluating different cutoff formulas and assay precision. Serum samples (n = 257) were tested for anti-HEV IgG and HEV RNA by nested RT-PCR and RT-qPCR. The overall anti-HEV seroprevalence was 26.5% (68/257) without the detection of HEV RNA. Most municipalities (53.3%) and farms (58.8%) had positive horses. Animals slaughtered for human consumption had higher risk of HEV exposure (45.5%) than those bred for sports or reproduction (6.4%) (p < 0.0001). The statistical analysis revealed sex and breeding system as possible risk-associated factors. The first serological evidence of HEV circulation in Brazilian equines reinforces the need for the surveillance of HEV host expansion in a one-health approach.

Investigation of the relationship between pulmonary lesions based on lung ultrasound and respiratory clinical signs in foals with suspected pulmonary rhodococcosis

Rhodococcus equi is a widely recognized bacterium responsible for pneumonia in preweaned foals. On endemic farms, foals with a subclinical course of the disease usually outnumber those presenting clinical signs. The disease is typically chronic and mainly manifests as fever and dyspnoea. Currently, field diagnosis is often based on lung ultrasound (LUS); however, both diagnostic and therapeutic approaches vary among practitioners and considerably change over time. This longitudinal, prospective study was designed to describe the appearance and progression of rhodococcal pulmonary lesions during the first months of life based on LUS and to evaluate the relationship between the presence and severity of rhodococcal pulmonary lesions and the occurrence of respiratory clinical signs in foals from farms with endemic R. equi infections. Nearly 26% of foals demonstrated respiratory signs highly suggestive of pulmonary rhodococcosis, and approximately 70% of the foals had abnormalities detected on LUS without concurrent clinical signs. The appearance and development of LUS abnormalities were age-related. An abscess diameter exceeding 15 mm in LUS and other pleural lesions were significantly linked with the occurrence of clinical signs suggestive of pulmonary rhodococcosis (P < 0.001) and may be considered predictive factors of rhodococcal pneumonia in foals.

Complete genome sequencing and comparative genomic analysis of three donkey Streptococcus equi subsp. equi isolates.

Streptococcus equi subspecies equi (S. equi) is the causative agent of strangles, which is one of the most common and highly contagious respiratory infectious illnesses in horses. Streptococcus equi (S. equi) is a horse-specific pathogen that originated from the closely related zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). Despite decades of research, the movement of genetic material across host-restricted diseases remains a mystery. Three S. equi donkey isolates (HTP133, HTP232, and HT1112) were recently isolated from a strangles epidemic on donkey farms in China's Xinjiang Province. In this study, we performed a comprehensive comparative analysis of these isolates using whole genome sequencing and compared them to the published genomic sequences of equine strain S. equi 4047 to uncover evidence of genetic events that shaped the evolution of these donkey S. equi isolates' genomes. Whole genome sequencing indicated that both strains were closely related, with comparable gene compositions and a high rate of shared core genomes (1788-2004). Our comparative genomic study indicated that the genome structure is substantially conserved across three donkey strains; however, there are several rearrangements and inversions when compared to the horse isolate S. equi 4047. The virulence factors conveyed by genomic islands and prophages, in particular, played a key role in shaping the pathogenic capacity and genetic diversity of these S. equi strains. Furthermore, we discovered that the HT133 isolate had a strong colonization ability and increased motility; the HT1112 isolates had a significantly higher ability for antimicrobial resistance and biofilm formation, and the HT232 isolate gained pathogenic specialization by acquiring a bacteriophage encoding hyaluronate lyase. In summary, our findings show that genetic exchange across S. equi strains influences the development of the donkey S. equi genome, offering important genetic insights for future epidemiological studies of S. equi infection.

Development and application of a competitive ELISA for the detection of antibodies against Salmonella Abortusequi in equids.

The high abortion rate associated with Salmonella Abortusequi (S. Abortusequi) infection in equids has re-emerged over the past 10 years and has caused serious economic losses to China. Our previous studies showed that the flagellin FljB gene could distinguish S. Abortusequi from most Salmonella serotypes. In this study, the flagellin antigen was used to develop a competitive enzyme-linked immunosorbent assay (cELISA) that could be used to detect both horse and donkey serum samples using a monoclonal antibody (MAb) that was found to bind to FljB. A cELISA was established using the purified MAb coating of the plate and incubation of the mixture of horseradish peroxidase (HRP)-conjugated FljB antigen with the undiluted serum sample. The performance of the cELISA and the tube agglutination test (TAT) assay was compared with respect to sensitivity and specificity, by testing a panel containing 660 S. Abortusequi-positive and 515 S. Abortusequi-negative serum samples, all of which had been characterized by Western blotting. Receiver operator characteristic (ROC) analyses were performed to determine the cutoff value and estimate the detection specificity (Sp) and sensitivity (Se). ROC analysis showed that the area under the ROC curve (AUC) values of cELISA [AUC = 0.9941; 95% confidence interval (CI), 0.9898-0.9984] were higher than those of TAT (AUC = 0.7705; 95% Cl, 0.7437-0.7972). A cutoff value of 39.5% was selected with Sp and Se values of 100 (95% Cl, 99.26-100.00) and 97.58 (95% Cl, 96.10-98.50), respectively. The cELISA has excellent futures compared with TAT, such as shortened detection time, no need for pre-treatment of sera, and easy interpretation of the results, and is more suitable for disease surveillance.

Commonality of Virulence-Promoting Function in Rhodococcus equi Virulence Associated Proteins (Vaps)

Rhodococcus equi is a Gram-positive facultative intracellular pathogen associated with life-threatening bronchopneumonial disease in foals. Key to R. equi’s intracellular survival in host macrophages is the production of virulence associated proteins (Vaps). Numerous vap genes are found on virulence plasmids isolated from different species, and the Vaps share a high degree of sequence identity. VapA has been extensively studied, and although vapK and vapN genes from other R. equi virulence plasmids have been shown to be essential for R. equi intracellular survival, their mode of action is less characterised. We, therefore, examined whether VapK and VapN worked mechanistically in the same way as VapA. Indeed, like VapA, VapK and VapN neutralised lysosomal pH and reduced lysosomal hydrolase activity. A loss of VapA and R. equi virulence could be regained by the presence of either VapK or VapN. The acid-neutralisation activity was also observed to a lesser extent with VapB. There was a differential activity across these virulence-promoting Vaps with the most “acid-neutralising” activity found with VapN, then VapA and K, and finally VapB. These data suggest that VapA production, which is often found in equine infections, can be substituted by VapK and B (produced by plasmids often found in porcine species) or VapN (produced by plasmids often isolated in bovine and human samples). These data imply that the molecular mechanism(s) that VapA uses to neutralise lysosomal acidity should also be seen in VapN and K which will help guide researchers in identifying their precise mode of action and aid the future development of targeted therapeutics.

Development of monoclonal antibodies against Rhodococcus equi virulence-associated protein N and their application to pathological diagnosis.

Since 2015, virulence-associated protein N (vapN)-positive Rhodococcus equi has been isolated from pyogenic lesions in ruminants in multiple countries, including Japan, supporting the widespread distribution of this pathogen in ruminants, and suggesting that VapN is responsible for the pathogenicity of this infection. However, no immunological diagnostic method has been established for this infection. In this study, we attempted to produce anti-VapN monoclonal antibodies and apply them to immunostaining methods. Mice were immunized intraperitoneally or subcutaneously with 5 µg of recombinant VapN (rVapN). After cell fusion and cloning by limiting dilution, we generated three anti-VapN antibody-producing hybridomas (4H4, 5C3, and 5G10). Next, VapN-based immunostaining was performed using a mouse model inoculated with rVapN, the JCM94-3 (VapN-producing) strain, or the JID03-27 (low-producing) strain. Positive reactions were observed in necrotic lesions in the liver and spleen, especially in the rVapN-treated and JCM94-3-treated groups. Immunostaining of goats (n = 2) and cattle (n = 3) presumed to be infected with vapN-positive R. equi was also positive in organs carrying necrotic lesions including the lungs, lymph nodes, abomasum, and ribs. The reactivity of immunostaining differed among the antibodies, with the 4H4 antibody exhibiting the best reactivity and allowing detection at low concentrations. However, the reactivity of the other two antibodies was improved by antigen retrieval treatment. Several known diseases cause necrotizing granuloma formation, and the immunological diagnostic method established in this study can be used to distinguish R. equi infection from similar diseases or identify infection in previously missed cases.IMPORTANCERhodococcus equi can cause infection in ruminants, and its pathogenicity is suggested to be associated with VapN. Despite its wide distribution, no immunological diagnostic method has been developed for VapN-producing R. equi. Against this background, we attempted to develop monoclonal antibodies targeting VapN and assess their application in immunostaining. In the study, mice were immunized with recombinant VapN, and cell fusion and cloning by limiting dilution permitted the generation of three antibody-producing hybridomas. The utility of the antibodies produced from the hybridomas in immunostaining was demonstrated using an infected mouse model, and the antibodies were further applied to previously reported cases of R. equi infection in goats and cattle. Although the 4H4 antibody induced the strongest reactions, the reactivity of two other antibodies was improved by antigen retrieval. Our monoclonal antibodies will be utilized to support the definitive diagnosis of suspected R. equi infection, including cases that were previously missed.

Molecular prevalence of Sarcocystis spp. and Toxoplasma gondii in slaughtered equids in Northern Tunisia.

Sarcocystis spp. and Toxoplasma gondii are two apicomplexan protozoa that infect a broad range of vertebrates, however, little is known about the infection of equids with these parasites. A total of 184 slaughtered equids from slaughterhouses of Bizerte and Tunis located in Northern Tunisia, were examined for meat infections with Sarcocystis spp. and T. gondii by PCR. The prevalence of infections with Sarcocystis spp. and T. gondii were 38% (95% CI: 31-45) and 39.7% (95% CI: 32.6-46.7), respectively. The highest prevalence of infection with Sarcocystis spp. was observed in donkeys (48.6%; 95%CI: 37.3-60) followed by mules (32.8%; 95%CI: 21.3-44.3), and horses (28.3%; 95%CI: 15.2-41.2) (p = 0.04). Similarly, the highest prevalence of infection with T. gondii was also observed in donkeys (66.2%; 95%CI: 55.4-77), followed by mules (18.7%; 95%CI: 9.2-28.3), and horses (26.1%; 95%CI: 13.4-38.8) (p<0.001). The co-infection prevalence was estimated to 17.4% (95%CI: 11.9-22.9). Taking into consideration that humans can be infected following consumption of infected equid meat with T. gondii and/or some Sarcocystis species, it is importance to assess the risk of human infection. Thus, further studies are needed to better understand the epidemiology of these zoonoses.

The Antiviral Factor SERINC5 Impairs the Expression of Non-Self-DNA.

SERINC5 is a restriction factor that becomes incorporated into nascent retroviral particles, impairing their ability to infect target cells. In turn, retroviruses have evolved countermeasures against SERINC5. For instance, the primate lentiviruses (HIV and SIV) use Nef, Moloney Murine Leukemia Virus (MLV) uses GlycoGag, and Equine Infectious Anemia Virus (EIAV) uses S2 to remove SERINC5 from the plasma membrane, preventing its incorporation into progeny virions. Recent studies have shown that SERINC5 also restricts other viruses, such as Hepatitis B Virus (HBV) and Classical Swine Fever Virus (CSFV), although through a different mechanism, suggesting that SERINC5 can interfere with multiple stages of the virus life cycle. To investigate whether SERINC5 can also impact other steps of the replication cycle of HIV, the effects of SERINC5 on viral transcripts, proteins, and virus progeny size were studied. Here, we report that SERINC5 causes significant defects in HIV gene expression, which impacts virion production. While the underlying mechanism is still unknown, we found that the restriction occurs at the transcriptional level and similarly affects plasmid and non-integrated proviral DNA (ectopic or non-self-DNA). However, SERINC5 causes no defects in the expression of viral RNA, host genes, or proviral DNA that is integrated in the cellular genome. Hence, our findings reveal that SERINC5's actions in host defense extend beyond blocking virus entry.

CANTERing towards more sustainable helminth control.

Victoria Colgate of Equine Infectious Disease Surveillance introduces CANTER, a voluntary pan-industry initiative that is aiming to inspire behaviour change among horse owners and promote a more sustainable approach to controlling parasites in their animals.

Worldwide Overview of Neospora spp. Infection in Equids Diagnosed by Serological Tests: Systematic Review and Meta-Analysis

Equids can be infected by Neospora spp., and its infection is associated with neurological and reproductive disorders. This systematic review and meta-analysis aimed to assess the prevalence of anti-Neospora caninum antibodies in horses, donkeys and mules worldwide between 2012 and 2022. Five scientific databases were consulted: MEDLINE, ScienceDirect, PubMed, LILACS and SciELO, using the descriptors “protozoan” or “neospora” AND “horses” or “donkeys” or “mules”. A total of 1909 studies were screened, and 25 studies met the inclusion criteria. The pooled prevalence of Neospora spp. infection in equids, based on a total of 11,076, was 8.34% (95% CI: 4.78–14.17%). Further analysis by species revealed no statistically significant difference in the prevalence of Neospora spp. infection across equids: 8.5% (95% CI 5.03–13.99%) in horses, 7.36% (CI 2.08–22.94%) in donkeys and 6.07% (95% CI 0.71–36.83%) in mules. Regarding diagnostic tests, the prevalence of Neospora spp. infection determined by the indirect fluorescent antibody test (IFAT) was 8.08% (95% CI: 3.74–16.61%), by the enzyme-linked immunosorbent assay (ELISA) was 7.91% (95% CI: 3.71–16.08%), and by the modified agglutination test (MAT) was 20% (95% CI: 15.37–25.60%). This meta-analysis provided valuable and comprehensive insights into the prevalence of Neospora spp. infection in horses, donkeys, and mules using serological detection methods. The results highlight the wide distribution of Neospora spp. infection in equids across all continents, indicating the importance of this infection. Transmission of the parasite can occur both horizontally (directly between animals) and vertically (from mother to offspring), further emphasizing the significance of understanding and managing this infection in equid populations.

Recombinant Salmonella enterica OmpX protein expression and its potential for serologically diagnosing Salmonella abortion in mares.

Salmonella abortion in mares is caused by Salmonella enterica subspecies enterica serovar abortus equi infection and is characterized by premature (abortion) or non-viable fetus birth. Although all horses are susceptible to infection, the condition is more often clinically manifested in pregnant mares, with most abortions recorded in young females. In addition, nonspecific clinical disease signs and poorly sensitive and effective bacteriological diagnostic methods hinder rapid and reliable infection diagnoses. Immunochemical methods such as enzyme-linked immunosorbent assay (ELISA) and immunochromatography assays can facilitate effective and rapid diagnoses. However, they require highly specific and active antigens and antibodies. This study aimed to generate a recombinant S. enterica outer membrane protein X (OmpX) and evaluate its suitability for serological diagnosis of Salmonella abortion in mares. Outer membrane protein X from the S. enterica antigen was synthesized de novo and expressed in Escherichia coli using the pET28 vector. Transformed E. coli cells were cultured under different conditions to detect recombinant OmpX (rOmpX) expression, and rOmpX purification and refolding were both conducted using metal affinity chromatography. Refolded and purified rOmpX was characterized by western blotting, liquid chromatography with tandem mass spectrometry, and ELISA. After optimized rOmpX expression, a 23 kDa molecular weight protein was identified. Amino acid sequence analysis using Mascot program suggested that these peptides were the OmpX protein from S. enterica. High specificity and diagnostic efficiency were recorded when rOmpX was used in ELISA against 89 serum samples from aborted and contact mares. Recombinant outer membrane protein, in comparison to the O antigen, demonstrated better diagnostic characteristics against sera from mares who aborted and contact horses.

A case of bacteremia and pneumonia caused by Streptococcus equi subspecies equi infection in a 70-year-old female following horse exposure in rural Wyoming

BackgroundThe occurrence of zoonotic infections following an animal exposure continues to be an important consideration for all patients, especially those within agricultural communities. Streptococcus equi subspecies equi (S. equi subsp. equi) is a bacteria known to cause a common infection called ‘Strangles’ in horses. This article highlights a new case of pneumonia and bacteremia in a patient caused by S. equi subsp. equi following strangles exposure in a horse. Rarely has there been reported horse to human transmission of subsp. equi.Case PresentationA 70-year-old woman attended a rural emergency department with complaints of dry heaving, fever, chills, shakes, and nausea and presented with a cough. She had undergone a screening colonoscopy two days prior with no other significant medical history. The patient had computed tomography (CT) evidence of a pneumonia and positive blood cultures growing S. equi subsp. equi consistent with bacteremia. The patient later disclosed the recent passing of her horse following its sudden illness six days prior to her emergency department presentation. She had cuddled and kissed the horse prior to its death. The patient was treated with IV lactated ringers during the initial evaluation and admission and also received IV piperacillin-tazobactam 4.5 g every eight hours intravenously during her hospital stay. She was transitioned to an oral antibiotic on discharge. Subsequent blood cultures drawn the day after discharge were negative for S. equi subsp. equi, indicating successful treatment of her bacteremia.ConclusionsThis report discusses an atypical presentation of S. equi subsp. equi infection in an otherwise healthy individual, manifesting as early sepsis, pneumonia, and bacteremia. The patient likely developed this infection following direct contact exposure to her horse who had died from presumed strangles a few days prior to her symptom onset. This case highlights the importance of investigating potential exposures to S. equi subsp. equi in rural areas, areas where farming and ranching are prevalent, particularly among individuals working with horses. It is especially important to acknowledge high risk populations such as immunocompromised individuals with signs and symptoms of meningitis or bacteremia.