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Feline leukemia virus (FeLV) is a major viral disease in cats, causing leukemia and lymphoma. The molecular detection of FeLV RNA and the DNA provirus are important for staging of the disease. However, the rapid immunochromatographic assay commonly used for antigen detection can only detect viremia at the progressive stage. In this study, nested recombinase polymerase amplification (nRPA) was developed for exogenous FeLV DNA provirus detection, and reverse transcriptase polymerase amplification (RT-RPA) was developed for the detection of FeLV RNA. The approaches were validated using 108 cats with clinicopathologic abnormalities due to FeLV infection, and from 14 healthy cats in a vaccination plan. The nRPA and RT-RPA assays could rapidly amplify the FeLV template, and produced high sensitivity and specificity. The FeLV detection rate in regression cats by nRPA was increased up to 45.8% compared to the rapid immunochromatographic assay. Hence, FeLV diagnosis using nRPA and RT-RPA are rapid and easily established in low resource settings, benefiting FeLV prognosis, prevention, and control of both horizontal and vertical transmission.

Although canine circovirus (CanineCV)-associated with gastroenteritis has been well documented, the virus is also detectable in the respiratory discharge of dogs with respiratory disease. In this study, an epidemiological approach was used to explore the association between the presence of CanineCV and respiratory symptoms in dogs. Respiratory swabs were collected from 76 healthy dogs and 114 dogs with respiratory illness and tested for CanineCV using conventional PCR (cPCR). Furthermore, lung tissues collected from 15 necropsied dogs showing pneumonia were tested using the real-time PCR (qPCR) and in situ hybridization (ISH) technique. A total of 8.95% (17/190) of dogs were CanineCV positive, with a significant association ( p  = 0.013) in dogs with respiratory signs. Four necropsied dogs were qPCR positive with the CanineCV-DNA labeling localized in tracheobronchial lymphoid cells (3/4), pulmonary parenchyma, capillary endothelia, and mononuclear cells harboring in alveoli (2/4). Full-length genome sequences of seven CanineCV strains were analyzed, indicating that the detected CanineCV genome clustered in the CanineCV-4 genotype. Genetic recombination was also evident in the replicase ( Rep ) gene. Although the role of CanineCV primarily affecting lung lesions could not be determined from this study, the presence of CanineCV DNA in pulmonary-associated cells indicated the potential association of the virus with canine respiratory disease; thus, linking causality must be examined in further studies.

Canine distemper virus (CDV), a pathogen causing fatal disease in a wide range of carnivores, can be classified into several geographically-related lineages. It is unclear how genetic recombination contributed to the evolution and emergence of the novel CDV strains and the evolutions of these strains are not fully yet investigated. In this study, the complete genome sequences of eight CDV viruses, isolated from domestic dogs in Thailand, were investigated. Interestingly, most of the identified CDV strains (CDV1-3, -5, -8 TH/2014) clustered as a novel Asia-4 lineage, while the CDV4, -6, -7 TH/2014 belonged to the Asia-1 lineage. Recombination analysis revealed that the CDV4 TH/2014 is a putative recombinant virus from the Asia-1 and America-2 parent viruses. In contrast, no recombination events were detected in the Asia-4 lineage, indicating that it is a distinctive lineage. Evolutionary analysis suggested that the CDV Asia-4 lineage had emerged since 1924 and shared common ancestor with the America-2 lineage. Pressure analysis revealed that CDV nucleotides were under negative selection pressure for its rapid adaptation. These findings demonstrate the evolution of CDV Asia-4 lineage and identified the Asia-1 recombination event. The information regarding genetic diversity of CDVs is essential for further CDV’s research and monitoring.

Canine kobuvirus (CaKoV) is a pathogen associated with canine gastrointestinal disease (GID). This study examined 327 rectal swabs (RS), including 113 from Vietnam (46 healthy, 67 with GID) and 214 from Thailand (107 healthy and 107 with GID). CaKoV was detected in both countries, with prevalences of 28.3% (33/113) in Vietnam and 7.9% (17/214) in Thailand. Additionally, CaKoV was found in both dogs with diarrhea and healthy dogs. CaKoV was mainly found in puppies under six months of age (30.8%). Co-detection with other canine viruses were also observed. The complete coding sequence (CDS) of nine Vietnamese and four Thai CaKoV strains were characterized. Phylogenetic analysis revealed a close genetic relationship between Vietnamese and Thai CaKoV strains, which were related to the Chinese strains. CDS analysis indicated a distinct lineage for two Vietnamese CaKoV strains. Selective pressure analysis on the viral capsid (VP1) region showed negative selection, with potential positive selection sites on B-cell epitopes. This study, the first of its kind in Vietnam, provides insights into CaKoV prevalence in dogs of different ages and healthy statuses, updates CaKoV occurrence in Thailand, and sheds light on its molecular characteristics and immune evasion strategies.

Background Canine pneumovirus (CPV) is a pathogen that causes respiratory disease in dogs, and recent outbreaks in shelters in America and Europe have been reported. However, based on published data and documents, the identification of CPV and its variant in clinically symptomatic individual dogs in Thailand through Asia is limited. Therefore, the aims of this study were to determine the emergence of CPV and to consequently establish the genetic characterization and phylogenetic analysis of the CPV strains from 209 dogs showing respiratory distress in Thailand. Results This study identified and described the full-length CPV genome from three strains, designated herein as CPV_CP13 TH/2015, CPV_CP82 TH/2016 and CPV_SR1 TH/2016, that were isolated from six dogs out of 209 dogs (2.9%) with respiratory illness in Thailand. Phylogenetic analysis suggested that these three Thai CPV strains (CPV TH strains) belong to the CPV subgroup A and form a novel lineage; proposed as the Asian prototype. Specific mutations in the deduced amino acids of these CPV TH strains were found in the G/glycoprotein sequence, suggesting potential substitution sites for subtype classification. Results of intragenic recombination analysis revealed that CPV_CP82 TH/2016 is a recombinant strain, where the recombination event occurred in the L gene with the Italian prototype CPV Bari/100–12 as the putative major parent. Selective pressure analysis demonstrated that the majority of the nucleotides in the G/glycoprotein were under purifying selection with evidence of positive selection sites. Conclusions This collective information on the CPV TH strains is the first evidence of CPV emergence with genetic characterization in Thailand and as first report in Asia, where homologous recombination acts as a potential force driving the genetic diversity and shaping the evolution of canine pneumovirus.

Background Anticholinesterase insecticides (antiChE), including organophosphates and carbamates, are widely used to control crop pests in agriculture, household pests, and animal parasites, making them a potential source of poisoning in both humans and animals. This retrospective study aimed to document the frequency of antiChE positive samples in animal specimens analysed at the Department of Veterinary Pharmacology, Faculty of Veterinary Science, Chulalongkorn University from January 1, 2019, to December 31, 2024 using a cholinesterase kit based on Ellman’s method, to raise awareness and mitigate the risk to non-target animals. Results During the study period, specimens from 61 animal cases involving accidental or environmental exposure were submitted for antiChE detection. Of these, 16 cases (26.2%) tested positive. Dogs accounted for the majority of positive cases (11/16; 68.75%), followed by chickens (2/16; 12.5%), cats (2/16; 12.5%), and one duck (1/16; 6.25%). Stomach ingesta were the most frequently submitted specimens and consistently yielded antiChE positive results in confirmed cases. Conclusion This study underscores the ongoing risk of cholinesterase inhibitors in domestic animals and avian species, which are non-target of these compounds. The cholinesterase kit proved to be a useful screening tool, particularly when ingestion was not directly observed. Stomach ingesta specimens were the most reliable sample type for detecting antiChE poisoning. This study provided reference data for future research on antiChE toxicosis among non-target species.

Background Anticoagulant rodenticides (ARs) are widely used worldwide to control rodent populations, yet their toxicity to nontarget animal species, such as dogs and cats, raises significant concerns. Until now, there has been no information about the occurrence status of ARs toxicosis in Thailand. This study presents occurrence data on ARs poisoning in animal specimens analysed at the Department of Veterinary Pharmacology, Faculty of Veterinary Science, Chulalongkorn University, Thailand. Data from January 1, 2018, to December 31, 2023, was collected retrospectively, focusing on confirmed ARs intoxication cases identified through chemical analysis using thin-layer chromatography (TLC) and spectrophotometry methods. Detailed information on animal species, ages, sex, and types of animal specimens analysed was included. Results During the study period, 35 cases (63.6%) out of 55 tested positive for ARs. Dogs accounted for 77.1% of the ARs-positive cases. Notably, specimens from wild animals and exotic pets, including a turkey, a wild boar, a goose, and three Patagonian mara, were also tested positive for ARs poisoning. Both liver and stomach content specimens showed high agreement in ARs detection, suggesting the potential utility of stomach content analysis alongside liver specimens, which has not been previously reported. Conclusions This retrospective study underscores the risk of ARs toxicosis in nontarget species. TLC and spectrophotometry methods serve as reliable screening tools for confirming ARs intoxication diagnosis. This study provided a reference for future research on the epidemiology on ARs toxicosis among nontarget species.

Hepatitis B virus (HBV) is a human pathogen of global concern, while a high diversity of viruses related to HBV have been discovered in other animals during the last decade. Recently, the novel mammalian hepadnavirus, tentatively named domestic cat hepadnavirus (DCH), was detected in an immunocompromised cat. Herein, a collection of 209 cat sera and 15 hepato-diseased cats were screened for DCH using PCR, resulting in 12.4% and 20% positivity in the tested sera and necropsied cats, respectively. Among the DCH-positive sera, a significantly high level of co-detection with retroviral infection was found, with the highest proportion being co-detection with feline immunodeficiency virus (FIV). Full-length genome characterization of DCH revealed the genetic diversity between the nine Thai DCH sequences obtained, and that they phylogenetically formed three distinct monophyletic clades. A putative DCH recombinant strain was found, suggesting a possible role of recombination in DCH evolution. Additionally, quantitative PCR was used to determine the viral copy number in various organs of the DCH-moribund cats, while the pathological findings were compared to the viral localization in hepatocytes, adjacent to areas of hepatic fibrosis, by immunohistochemical (IHC) and western blot analysis. In addition to the liver, positive-DCH immunoreactivity was found in various other organs, including kidneys, lung, heart, intestine, brain, and lymph nodes, providing evidence of systemic infection. Ultrastructure of infected cells revealed electron-dense particles in the nucleus and cytoplasm of hepatocytes, bronchial epithelial cells, and fibroblasts. We propose the intracellular development mechanism of this virus. Although the definitive roles of pathogenicity of DCH remains undetermined, a contributory role of the virus associated with systemic diseases is possible.

Background Canine respiratory coronavirus (CRCoV) is a major contributor to the canine infectious respiratory disease complex (CIRDC). Despite its widespread prevalence, molecular assays for CRCoV detection remain limited. Additionally, the efficiency and accuracy of detection can vary depending on the type of clinical sample used, such as nasal swabs (NS), oropharyngeal swabs (OS), and rectal swabs (RS). To address these challenges, we developed a nanoplate-based reverse transcription digital polymerase chain reaction (RT-dPCR) method for detecting the spike gene of CRCoV in various clinical samples. Results The RT-dPCR assay demonstrated consistent repeatability and reproducibility, ensuring reliable results. With a detection limit of 1.83 copies/µL, the RT-dPCR assay exhibited 100-fold greater sensitivity than probe-based reverse transcription quantitative polymerase chain reaction (RT-qPCR). It showed no cross-reactivity with other common CIRDC-associated viruses or coronaviruses, confirming its high specificity for CRCoV. The assay was further validated using 162 clinical swab samples (NS, OS, and RS) collected from both healthy dogs and those with respiratory distress. The RT-dPCR assay showed a higher overall positivity rate for CRCoV compared to RT-qPCR, with the most notable difference observed in rectal swabs ( P  < 0.05), where RT-dPCR detected CRCoV in 53.7% of samples compared to 22.22% by RT-qPCR. Conclusions This study demonstrated that the RT-dPCR assay provided high sensitivity for detecting low viral loads across various sample types, making it a valuable tool for precise CRCoV detection. In contrast, RT-qPCR remains valuable for its broader detection range and suitability in initial screening. Both techniques proved to be versatile tools that can contribute to advancing CRCoV research and improving clinical diagnostics.

Background Anticoagulant rodenticide (AR) poisoning was diagnosed in 3 Patagonian maras ( Dolichotis patagonum ) raised in the mara farm in Thailand. To date, there have been no reports of maras with diagnosed AR poisoning. Case presentation The first clinical sign of the sickening maras was anorexia. Fifteen from 50 maras were dead over a 3–5 day period after the clinical signs had occurred. Positive results to AR were detected in all of the maras’ liver specimens by screening test using thin layer chromatography and spectrophotometry methods. Supportive therapy was selected for the treatment of the 35 surviving maras. During the follow – up observation period of 12 months, all of the surviving maras were healthy and no reproductive loss. Conclusions This is the first report on suspected AR poisoning in maras in Thailand based on history taking, clinical signs, gross pathology lesions and chemical analysis. AR poisoning in the present report is possibly from contaminated animal food. Therefore, quality control of food should be fastidious when feeding maras.