African Horse Sickness Virus Serotype 1 on Horse Farm, Thailand, 2020.

To investigate an outbreak of African horse sickness (AHS) on a horse farm in northeastern Thailand, we used whole-genome sequencing to detect and characterize the virus. The viruses belonged to serotype 1 and contained unique amino acids (95V,166S, 660I in virus capsid protein 2), suggesting a single virus introduction to Thailand.

Oral fluid samples used for PRRSV acclimatization program and sow performance monitoring in endemic PRRS-positive farms.

An effective gilt acclimatization program is one of the most important management strategies for controlling porcine reproductive and respiratory syndrome virus (PRRSV) infection. Recently, oral fluid samples have been used as alternative diagnostic samples for various swine diseases. This study utilized oral fluids for PRRSV monitoring during the gilt acclimatization period in PRRSV endemic farms. The study was performed in two selected commercial breeding herds (farm A and farm B). PRRSV RNA and PRRSV-specific antibodies were monitored using oral fluid and serum samples. Sow performance parameters related to PRRSV infection were recorded and assessed. After PRRSV exposure during acclimatization, viral RNA was demonstrated in oral fluids from 1 to 10 weeks post-exposure (WPE). PRRSV RNA was detected in serum at 1 and 4 WPE in farm A and at 1, 4, 8, and 12 WPE in farm B. Prolonged viremia of gilts from farm B was possibly due to re-infection (within the herd) and later, reproductive problems were found in the breeding herd. The correlation of PRRSV RNA concentration in oral fluids and serum was evident. The S/P ratio values of PRRSV antibodies in oral fluid samples were higher and had similar patterns of antibody responses to the serum samples. The results suggest that the use of oral fluid samples for PRRSV monitoring during gilt acclimatization in endemic farms is effective, convenient, practical, and economical and would be most beneficial when used with other parameters.

Efficacy of a type 2 PRRSV modified live vaccine (PrimePac™ PRRS) against a Thai HP-PRRSV challenge.

The Chinese highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) has caused a severe threat to the pig population in Southeast Asian countries. The purpose of this study was to investigate the efficacy of a type 2 PRRSV modified live vaccine (PrimePac™ PRRS, lineage 7) against a Thai HP-PRRSV (10PL01, lineage 8). Three-week-old PRRSV-free pigs were randomly assigned into three groups. Vaccinated challenged group (group 1, n = 16) was immunized with PrimePac™ PRRS vaccine at 3 weeks old. The unvaccinated challenged group (group 2, n = 16) was injected with PBS at 3 weeks old, and unvaccinated unchallenged group (group 3, n = 10) was served as a negative control. At 9 weeks old, all groups, except the negative control group, were challenged with the Thai HP-PRRSV. All pigs were monitored daily during 10 days post-infection (dpi) and were necropsied at 10 and 17 dpi. The results revealed that vaccinated challenged pigs showed significantly lower (p < 0.05) mean rectal temperatures, clinical respiratory scores, lung lesion scores, and levels of virus load in serum and lung tissue compared with the unvaccinated challenged pigs. Moreover, vaccinated challenged pigs exhibited PRRSV-specific serum neutralizing antibodies at the end of the experiment. Our findings indicated that the studied type 2 PRRSV vaccine provided partial protection against the Thai HP-PRRSV infection based on the body temperature, levels of viremia, and the severity of lung lesions. These results demonstrated that partial protection of PrimePac™ PRRS vaccine might be useful for controlling HP-PRRSV infection in the endemic area.

Interleukin-1 receptor antagonist: an early immunomodulatory cytokine induced by porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome virus (PRRSV) infection poorly induces pro-inflammatory cytokines (IL-1, IL-6 and TNF-α) and type I IFN production during the early phase of infection. Our microarray analysis indicated strong upregulation of the IL1RA gene in type 2 PRRSV -infected monocyte-derived dendritic cells. Interleukin-1 receptor antagonist (IL-1Ra) is an early inhibitory cytokine that suppresses pro-inflammatory cytokines and T-lymphocyte responses. To investigate the induction of IL-1Ra by PRRSV, monocyte-derived dendritic cells were cultured with type 2 PRRSV or other swine viruses. PRRSV increased both IL1RA gene expression and IL-1Ra protein production in the culture. The enhanced production of IL-1Ra was further confirmed in PRRSV-cultured PBMC and PRRSV-exposed pigs by flow cytometry. Myeloid cell population appeared to be the major IL-1Ra producer both in vitro and in vivo. In contrast to the type 2 PRRSV, the highly pathogenic (HP)- PRRSV did not upregulate IL1RA gene expression in vitro. To determine the kinetics of PRRSV-induced IL1RA gene expression in relation to other pro-inflammatory cytokine genes, PRRSV-negative pigs were vaccinated with a commercially available type 2 modified-live PRRS vaccine or intranasally inoculated with HP-PRRSV. In modified-live PRRS vaccine pigs, upregulation of IL1RA, but not IL1B and IFNA, gene expression was observed from 2 days post- vaccination. Consistent with the in vitro findings, upregulation of IL1RA gene expression was not observed in the HP-PRRSV-infected pigs throughout the experiment. This study identified IL-1Ra as an early immunomodulatory mediator that could be involved in the immunopathogenesis of PRRSV infections.

Efficacy of Fostera® PRRS modified live virus (MLV) vaccination strategy against a Thai highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) infection.

Recently, the Chinese highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) (HP-PRRSV) belonging to lineage 8 causes severe symptom with high morbidity and high mortality rates to the Asian pig industry. A recent study showed that pigs immunized with Fostera® PRRS modified live virus (MLV) of lineage 8 could provide a degree of protection against a Vietnamese HP-PRRSV infection. It should be noted that PRRSV commonly found after weaning causes porcine respiratory disease complex (PRDC). Vaccination strategy should be evaluated in each farm scenario. Eighty-one PRRSV-free piglets obtained from a PRRS-free herd were divided into two experiments with the major difference of infection timing after vaccination, 42 days in experiment 1 (n = 42) and 28 days in experiment 2 (n = 39). Each experiment had similar protocol containing three groups including a negative control, unvaccinated challenged, and vaccinated challenged groups. Pigs in vaccination groups were immunized with Fostera® PRRS MLV vaccine at 3 weeks of age. Then, unvaccinated challenged and vaccinated challenged groups were intranasally inoculated with a Thai HP-PRRSV (10PL01). Vaccinated challenged pigs showed significantly lower levels of mean rectal temperatures, clinical severity, lung lesion scores, and viral titers in serum and lung tissue compared to the unvaccinated challenged pigs (p < 0.05). Vaccinated challenged pigs had higher survival rate than those of unvaccinated challenged pigs in both experiments. It should be noted that pigs challenged 42 days after vaccination showed a better performance than pigs challenged 28 days after vaccination. In conclusion, Fostera® PRRS MLV vaccine was able to improve the survival rate against the Thai HP-PRRSV infection in both 42- and 28-day vaccination-to-infection protocols.

Genetic characterization of canine influenza A virus (H3N2) in Thailand.

In January 2012, several clinical cases of dogs with flu-like symptoms, including coughing, sneezing, nasal discharge, and fever, were reported in a small-animal hospital located in Bangkok, Thailand. One influenza A virus was identified and characterized as an avian-like influenza virus H3N2. The virus was named A/canine/Thailand/CU-DC5299/12. A phylogenetic analysis indicated that the canine virus belonged to an avian Eurasian lineage and was genetically related to the canine influenza viruses H3N2 from China and Korea. This canine virus displays a unique genetic signature with two amino acid insertions in the NA protein, which is similar to the canine influenza viruses from eastern China (Zhejiang and Jiangsu). This study constitutes the first report of H3N2 canine influenza virus infection in a small-animal hospital in Thailand.

Reproductive performance of sows with and without PRRS modified live virus vaccination in PRRS-virus-seropositive herds.

Porcine reproductive and respiratory syndrome (PRRS) virus infection causes reproductive failures including return to oestrus, abortion, mummified foetuses, stillborn, and weak-born piglets. The objective of the present study was to investigate reproductive performance of sows in PRRS-virus-seropositive herds with and without PRRS modified live virus (PRRS-MLV) vaccination. The study was conducted in 20 PRRS-virus-seropositive commercial swine herds in Thailand. The data included 211,009 mating and 180,935 farrowing records. The analysed variables included farrowing rate (FR), return rate (RR), abortion rate (AR), total number of piglets born per litter (TB), number of piglets born alive per litter (BA), percentage of stillborn (SB), percentage of mummified foetuses (MM), and number of piglets weaned per litter (WP). The results revealed that FR in non-vaccinated sows was lower than that in vaccinated sows (85.0 vs 89.7%, respectively, P < 0.001), and RR in non-vaccinated sows was higher than that in vaccinated sows (6.9 vs 3.7%, respectively, P < 0.001). AR did not differ significantly between non-vaccinated and vaccinated sows (1.6 and 2.0%, respectively, P = 0.964). TB (11.2 and 11.5, respectively, P < 0.001), BA (10.0 and 10.6, respectively, P < 0.001), and WP (9.2 and 9.6, respectively, P < 0.001) in non-vaccinated sows were lower than those in vaccinated sows. SB (6.9 and 5.1%, respectively, P < 0.001) and MM (3.2 and 2.2%, respectively, P < 0.001) in PRRS-MLV-vaccinated sows were higher than those in non-vaccinated sows. The improvement in sow reproductive performance in PRRS-MLV-vaccinated herds was most pronounced in gilts and primiparous sows.

Experimental infection with a Thai reassortant swine influenza virus of pandemic H1N1 origin induced disease.

BACKGROUND: Following the emergence of the pandemic H1N1 influenza A virus in 2009 in humans, this novel virus spread into the swine population. Pigs represent a potential host for this virus and can serve as a mixing vessel for genetic mutations of the influenza virus. Reassortant viruses eventually emerged from the 2009 pandemic and were reported in swine populations worldwide including Thailand. As a result of the discovery of this emergent disease, pathogenesis studies of this novel virus were conducted in order that future disease protection and control measures in swine and human populations could be enacted. METHODS: The pandemic H1N1 2009 virus (pH1N1) and its reassortant virus (rH1N1) isolated from pigs in Thailand were inoculated into 2 separate cohorts of 9, 3-week-old pigs. Cohorts were consisted of one group experimentally infected with pH1N1 and one group with rH1N1. A negative control group consisting of 3 pigs was also included. Clinical signs, viral shedding and pathological lesions were investigated and compared. Later, 3 pigs from viral inoculated groups and 1 pig from the control group were necropsied at 2, 4, and 12 days post inoculation (DPI). RESULTS: The results indicated that pigs infected with both viruses demonstrated typical flu-like clinical signs and histopathological lesions of varying severity. Influenza infected-pigs of both groups had mild to moderate pulmonary signs on 1-4 DPI. Interestingly, pigs in both groups demonstrated viral RNA detection in the nasal swabs until the end of the experiment (12 DPI). CONCLUSION: The present study demonstrated that both the pH1N1 and rH1N1 influenza viruses, isolated from naturally infected pigs, induced acute respiratory disease in experimentally inoculated nursery pigs. Although animals in the rH1N1-infected cohort demonstrated more severe clinical signs, had higher numbers of pigs shedding the virus, were noted to have increased histopathological severity of lung lesions and increased viral antigen in lung tissue, the findings were not statistically significant in comparison with the pH1N1-infected group. Interestingly, viral genetic material of both viruses could be detected from the nasal swabs until the end of the experiment. Similar to other swine influenza viruses, the clinical signs and pathological lesions in both rH1N1 and pH1N1 were limited to the respiratory tract.

Genetic characterization of Thai swine influenza viruses after the introduction of pandemic H1N1 2009.

Pandemic H1N1 2009 (pH1N1), influenza virus containing triple reassortant internal genes (TRIG) from avian, human, and swine influenza viruses emerged in 2009 as a highly infectious virus that was able to be transmitted from humans to pigs. During June 2010-May 2012, influenza virus surveillance was conducted in Thai pig population. Twenty-three samples (1.75%) were successfully isolated from total of 1,335 samples. Interestingly, pH1N1 (7 isolates, 30.34%), reassortant pH1N1 (rH1N1) (1 isolate, 4.35%), Thai endemic H1N1 (enH1N1) (3 isolates, 13.04%), reassortant H3N2 with pH1N1 internal genes (rH3N2) (9 isolates, 39.13%), and reassortant H1N2 with pH1N1 internal genes (rH1N2) (3 isolates, 13.04%) were found. It should be noted that rH1N1, rH1N2, and rH3N2 viruses contained the internal genes of pH1N1 virus having a TRIG cassette descendant from the North American swine lineage. Although all isolates in this study were obtained from mild clinically sick pigs, the viruses were still highly infective and possibly may play an important role in human-animal interfacing transmission. In addition, the TRIG cassette may have an influence on antigenic shift resulting in emergence of novel viruses, as seen in this study. Continuing surveillance of influenza A natural hosts, particularly in pigs is necessary.

Reproductive parameters following a PRRS outbreak where a whole-herd PRRS MLV vaccination strategy was instituted post-outbreak.

This study assessed the effect of whole-herd porcine reproductive and respiratory syndrome (PRRS) modified-live virus (MLV) vaccination on herd-level reproductive performance, PRRS virus (PRRSV) viremia, and antibody in a subset of females in a 1,200-sow commercial herd in Thailand. Following a PRRSV outbreak, the entire herd was vaccinated with PRRS MLV twice at 3-week intervals and at 3-month intervals, thereafter. Reproductive performance data over a 3-year period were available for analysis. Serum samples were collected before and after vaccination and tested by PRRSV ELISA and reverse transcription-polymerase chain reaction. Vaccination was statistically associated with a lower abortion rate (1.4 vs. 1.6 %), farrowing rate (83.8 vs. 90.0 %), total born (10.6 vs. 11.4 piglets/litter), liveborn (10.0 vs. 10.3 piglets/litter), stillbirths (4.6 vs. 7.0 %), mummies (0.7 vs. 1.6 %), and a higher return rate (11.3 vs. 5.9 %) when compared with the period before the PRRSV outbreak. Pregnant females vaccinated during early gestation farrowed fewer liveborn and more mummies than the comparison group, whereas females vaccinated during late gestation had a lower farrowing rate. In this herd, PRRS whole-herd vaccination had neutral, positive, and negative effects on reproductive performance. Thus, the decision to implement whole-herd vaccination should be balanced between the benefits derived from reproductive performance improvements, e.g., fewer abortions, stillborn piglets, and mummified fetuses, and the effect of vaccination on pregnant females.

Emergence of novel porcine circovirus 2d strains in Thailand, 2019-2020.

Porcine circovirus 2 (PCV2) has been recognized as a causative agent of porcine circovirus diseases (PCVDs) affecting the global swine industry. In this study, the genetic diversity of PCV2 strains circulating in Thailand between 2019 and 2020 was investigated using 742 swine clinical samples from 145 farms. The results showed PCV2-positive rates of 54.2% (402/742) and 81.4% (118/145) at the sample and farm levels, respectively. Genetic analysis of 51 Thai PCV2 genomic sequences showed that 84.3% (43/51) was PCV2d, 13.7% (7/51) was PCV2b and 1.9% (1/51) was PCV2b/2d recombinant virus. Surprisingly, the majority of the Thai PCV2d sequences from this study (69.77%, 30/43) formed a novel cluster on a phylogenetic tree and contained a unique 133HDAM136 on the ORF2 deduced amino acid sequence, which is in one of the previously identified immunoreactive domains strongly involved in virus neutralization. The PCV2b/2d recombinant virus also carried 133HDAM136. The emergence of the novel PCV2d strains predominating in Thailand was discussed. This study highlights the need for further investigations on the spreading of these PCV2d strains in other regions and the efficacy of current commercial vaccines.

Molecular detection and genetic characterization of porcine circovirus 4 (PCV4) in Thailand during 2019-2020.

Porcine circovirus 4 (PCV4) is considered a novel PCV, firstly found in China in 2019 and later discovered in Korea. This present study investigated the prevalence and genetic characteristics of PCV4 from high pig-density areas in Thailand during 2019-2020. From 734 samples, three samples (0.4%) from aborted fetuses and porcine respiratory disease complex (PRDC) cases were found positive for PCV4, two of the PCV4-positive samples were coinfected with both PCV2 and PRRSV, and the other PCV4-positive sample was found coinfected with PCV2. In situ hybridization (ISH) revealed the presence of PCV4 in the bronchial epithelial cells and in lymphocytes and histiocyte-like cells in the lymphoid follicles of the PRDC-affected pig. The complete Thai PCV4 genome had over 98% nucleotide identity with other PCV4 strains and was closely related to the Korean and Chinese PCV4b strains. Importantly, the amino acid residue at position 212 of the Cap gene is recommended for differentiating PCV4a (212L) from PCV4b (212M) based on currently available PCV4 genome sequences. These findings provide important clues for the pathogenesis, epidemiology, and genetic characteristics of PCV4 in Thailand.

Comparative Efficacy of Chimeric Porcine Circovirus (PCV) Vaccines against Experimental Heterologous PCV2d Challenges.

The objective of this study was to evaluate the efficacy of two multivalent commercial porcine circovirus (PCV) vaccines against heterologous PCV2d challenges. A total of 24 crossbred male pigs aged 26 days selected from a specific pathogen-free herd were randomly divided into four groups (six pigs per group) and assigned as follows: negative control (unvaccinated/sham-challenge), vaccinated with chimeric PCV1-2a vaccine (PCV1-2a/PCV2d-challenge), vaccinated with chimeric PCV1-2a-2b vaccine (PCV1-2a-2b/PCV2d-challenge) and positive control (unvaccinated/PCV2d-challenge). At 21 days after vaccination, the pigs were intranasally and intramuscularly inoculated with either sham or field isolates of PCV2d (PCV2d/149/TH/2020). After being challenged, blood samples were obtained weekly and analyzed for levels of PCV2d viremia, neutralizing antibodies, and IgG against PCV2. At 30 days post-challenge (DPC), the pigs were euthanized and then subjected to pathological evaluations and molecular analysis. The results indicated that pigs in the PCV1-2a-2b/PCV2d-challenge and the PCV1-2a/PCV2d-challenge groups possessed significantly greater levels of PCV2d-neutralizing antibody titer when compared with the positive control group. Moreover, pigs in the PCV1-2a-2b/PCV2d-challenge group exhibited a lower degree of severity in terms of gross lesion scores and lower levels of PCV2 viremia when compared with the positive control group. This study demonstrated that vaccinating pigs with either the PCV1-2a or PCV1-2a-2b chimeric vaccines elicits a potent immune response against PCV2d infection and reduces viremia after PCV2d inoculation in pigs.

Response of elephant peripheral blood mononuclear cells when stimulated with elephant endotheliotropic herpesvirus glycoprotein B (EEHV-gB).

Elephant endotheliotropic herpesvirus-hemorrhagic disease (EEHV-HD) is the most highly fatal infectious disease among young Asian elephants. Despite the fact that antiviral therapy has been widely used, its therapeutic outcomes remain uncertain. Additionally, the virus has yet to be successfully cultivated in vitro in the process of develop viral envelope glycoproteins for vaccine design. The present study aims to investigate and evaluate EEHV1A glycoprotein B (gB) antigenic epitopes as potential candidates for further vaccine development. Epitopes of EEHV1A-gB were employed in in silico predictions and designed by using online antigenic predicting tools. Candidate genes were then constructed, transformed and expressed in the E. coli vectors prior to examine their potential for acceleration elephant immune responses in vitro. Elephant peripheral blood mononuclear cells (PBMCs) isolated from 16 healthy juvenile Asian elephants were investigated for their proliferative capability and cytokine responses after being stimulated with EEHV1A-gB epitopes. Exposure of elephant PBMCs to 20 µg/mL of gB for 72 h resulted in a significant proliferation of CD3 + cells when compared with the control group. Furthermore, proliferation of CD3 + cells was associated with a marked up-regulation of cytokine mRNA expression, involving IL-1ß, IL-8, IL-12 and IFN-γ. It remains to be determined whether these candidate EEHV1A-gB epitopes could activate immune responses in animal models or elephants in vivo. Our potentially promising results demonstrate a degree of feasibility for the use of these gB epitopes in expanding EEHV vaccine development.

Performance of a Differentiation of Infected from Vaccinated Animals (DIVA) Classical Swine Fever Virus (CSFV) Serum and Oral Fluid Erns Antibody AlphaLISA Assay.

Classical swine fever virus (CSFV) is an OIE-listed disease that requires effective surveillance tools for its detection and control. The aim of this study was to develop and evaluate the diagnostic performance of a novel CSFV Erns IgG AlphaLISA for both serum and oral fluid specimens that would likewise be compatible with the use of CSFV E2 DIVA vaccines. Test performance was evaluated using a panel of well-characterized serum (n = 760) and individual (n = 528) or pen-based (n = 30) oral fluid samples from four groups of animals: (1) negative controls (n = 60 pigs); (2) inoculated with ALD strain wild-type CSFV (n = 30 pigs); (3) vaccinated with LOM strain live CSFV vaccine (n = 30 pigs); and (4) vaccinated with live CSFV marker vaccine on commercial farms (n = 120 pigs). At a cutoff of S/P ≥ 0.7, the aggregate estimated diagnostic sensitivities and specificities of the assay were, respectively, 97.4% (95% CI 95.9%, 98.3%) and 100% for serum and 95.4% (95% CI 92.9%, 97.0%) and 100% for oral fluid. The Erns IgG antibody AlphaLISA combined DIVA capability with solid diagnostic performance, rapid turnaround, ease of use, and compatibility with both serum and oral fluid specimens.

Role of porcine reproductive and respiratory syndrome virus nucleocapsid protein in induction of interleukin-10 and regulatory T-lymphocytes (Treg).

Porcine reproductive and respiratory syndrome virus (PRRSV) infection induces interleukin (IL)-10 production and increased numbers of PRRSV-specific regulatory T-lymphocytes in infected pigs. In the present study, the roles of the nucleocapsid (N) protein in induction of IL-10 and CD4(+)CD25(+)Foxp3(+) lymphocytes (T(reg)) were investigated. Transfection of porcine monocyte-derived dendritic cells (MoDCs) and pulmonary alveolar macrophages (PAMs) with a plasmid encoding N protein resulted in significant upregulation of IL-10 gene expression in the gene-transfected cells. Structural conformation, but not nuclear localization, of the expressed N protein was indicated to be essential for the ability to induce IL-10. Furthermore, the presence of recombinant N proteins in cultured PBMCs increased the number of IL-10-producing lymphocytes. Strong induction of IL-10-producing cells and T(reg) was observed when using N protein-pulsed MoDCs, suggesting an important role of MoDCs in induction of IL-10 and T(reg) by the N protein. Neutralization of IL-10 by addition of an anti-IL-10 antibody in the culture system resulted in marked reduction of PRRSV-induced T(reg) in the cultured PBMCs. Together, the data demonstrate the immunomodulatory properties of the PRRSV N protein and the linkage between IL-10 production and development of PRRSV-induced T(reg). Our results reveal an immunomodulatory function of the PRRSV N protein that may contribute to the unique immunological outcome observed following PRRSV infection.

Comparison of detection procedures of Mycoplasma hyopneumoniae, Mycoplasma hyosynoviae, and Mycoplasma hyorhinis in lungs, tonsils, and synovial fluid of slaughtered pigs and their distributions in Thailand.

The aim of this study was to investigate whether direct PCR (DP) gave similar results to culture prior to PCR (CPP) for detecting mycoplasmas in different types of pig tissues. A total of 724 samples obtained from lungs, tonsils, or synovial fluids from 270 slaughtered pigs were used. The history of clinical signs, lung score, and the presence of joint lesions were recorded during sample collection. The rates of detection of Mycoplasma hyopneumoniae, Mycoplasma hyosynoviae, and Mycoplasma hyorhinis using both procedures were evaluated. The overall prevalences of M. hyopneumoniae, M. hyosynoviae, and M. hyorhinis were 40.3%, 12.3%, and 64.6%, respectively, and the detection rate depended on the sample type and the procedure used. With lung tissue, DP gave a higher detection rate for M. hyopneumoniae (77.4%) than CPP (38.5%). M. hyorhinis was detected by CPP at 15.6% and 18.1% and by DP at 31.5% and 5.2%, respectively. The positive rate derived from tonsil from CPP was closed to that of DP. Using synovial fluid could not yield any positive M. hyorhinis from CPP whereas 37.2% was positive from DP. In contrast, using sample tissue from lung and tonsil by CPP could show much higher positive number than that of DP. There was a significant relationship between joint lesion and M. hyorhinis detection by DP (P < 0.05) but not for M. hyosynoviae and M. hyorhinis detected by CPP. We speculated that lung was a proper sample for M. hyopneumoniae and M. hyorhinis detection by DP and CPP, respectively. Tonsil was likely the community of persistent M. hyosynoviae and M. hyorhinis with highly detection by CPP. Synovial fluid was apparently unsuitable for mycoplasmal culture. The accuracy of mycoplasmal detection may depend upon the type of sample relevant to the detection procedure used.

Porcine respiratory disease complex: Dynamics of polymicrobial infections and management strategies after the introduction of the African swine fever.

A few decades ago, porcine respiratory disease complex (PRDC) exerted a major economic impact on the global swine industry, particularly due to the adoption of intensive farming by the latter during the 1980's. Since then, the emerging of porcine reproductive and respiratory syndrome virus (PRRSV) and of porcine circovirus type 2 (PCV2) as major immunosuppressive viruses led to an interaction with other endemic pathogens (e.g., Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Streptococcus suis, etc.) in swine farms, thereby exacerbating the endemic clinical diseases. We herein, review and discuss various dynamic polymicrobial infections among selected swine pathogens. Traditional biosecurity management strategies through multisite production, parity segregation, batch production, the adoption of all-in all-out production systems, specific vaccination and medication protocols for the prevention and control (or even eradication) of swine diseases are also recommended. After the introduction of the African swine fever (ASF), particularly in Asian countries, new normal management strategies minimizing pig contact by employing automatic feeding systems, artificial intelligence, and robotic farming and reducing the numbers of vaccines are suggested. Re-emergence of existing swine pathogens such as PRRSV or PCV2, or elimination of some pathogens may occur after the ASF-induced depopulation. ASF-associated repopulating strategies are, therefore, essential for the establishment of food security. The "repopulate swine farm" policy and the strict biosecurity management (without the use of ASF vaccines) are, herein, discussed for the sustainable management of small-to-medium pig farms, as these happen to be the most potential sources of an ASF re-occurrence. Finally, the ASF disruption has caused the swine industry to rapidly transform itself. Artificial intelligence and smart farming have gained tremendous attention as promising tools capable of resolving challenges in intensive swine farming and enhancing the farms' productivity and efficiency without compromising the strict biosecurity required during the ongoing ASF era.

Current Understanding of the Pathogenesis of Porcine Circovirus 3.

Circoviruses are closed, circular, single-stranded DNA viruses belonging to the family Circoviridae and the genus Circovirus. To date, at least four porcine circoviruses (PCVs) have been recognized, including PCV1 to PCV4, respectively. Similar to PCV2 pathogenesis, PCV3 has been reported worldwide with myriad clinical and pathological presentations such as reproductive disorders, respiratory diseases, diarrhea etc. Current understanding of PCV3 pathogenesis is very limited since the majority of studies were mostly field observations. Interpretation of the results from such studies is not always simple. Various confounding factors affect the clinical appearance and pathological changes of the infected pigs. Recently, several experimental PCV3 infection studies have been reported, providing a better understanding of its pathogenesis. In this review, we focused on novel findings regarding PCV3 pathogenesis from both field observation and experimental infection studies. Possible factors involved in the conflicting results among the experimental infection studies are also discussed. This review article provides important insight into the current knowledge on PCV3 pathogenesis which would aid in prioritizing research in order to fill the knowledge gaps.

Development of Nonstructural Protein-Based Indirect ELISA to Identify Elephant Endotheliotropic Herpesvirus (EEHV) Infection in Asian Elephants (Elephas maximus).

Disease caused by elephant endotheliotropic herpesvirus (EEHV) infection is the most highly fatal hemorrhagic disease in Asian elephant calves worldwide. To date, adult elephants that have been infected with EEHV have predominantly displayed mild clinical signs, while they are believed to serve as EEHV shedders to other elephants. Hence, the diagnostic tools employed for monitoring EEHV-active infection are considered vitally important. In this study, partial EEHV-DNA polymerase (DNApol) nonstructural proteins (NSPs) were used to detect anti-EEHV antibodies through the use of an in-house indirect enzyme-linked immunosorbent assay (ELISA). The results were then compared to those obtained from a PCR test. In this study, a total of 175 serum samples were collected from Asian elephants living in elephant camps located in Chiang Mai and Lampang Provinces, Thailand. The elephants were aged between 2 and 80 years old. The overall percentages of positive samples by the PCR and EEHV-DNApol ELISA tests were 4% (21/175) and 12% (21/175), respectively. The ELISAs demonstrated values of 77.9% (95% posterior probability interval (PPI) = 52.5-95%) sensitivity and 87.7% (PPI = 82.5-91.9%) specificity, respectively. Accordingly, the sera obtained from the elephants exhibiting no clinical signs of EEHV infection, and those who were negative according to PCR tests, revealed a value of 14% seropositivity for EEHV-DNApol. Our results indicate that these asymptomatic, active EEHV-infected elephants could likely serve as a source of EEHV shedding within elephant herds. Consequently, the developed EEHV-DNApol NSPs-based ELISA test employed in the present study may be of use for routine monitoring and identification of EEHV shedders in elephant herds, and could be an alternative diagnostic tool for EEHV detection in Asian elephants.