Infected Pigs Research Articles

Bacterial translocation and gut microbiome imbalance in an experimental infection model of legionellosis in guinea pigs

BackgroundRecent studies have shown that in critically ill patients such as those with sepsis and shock, the lung and gut microbiomes undergo profound changes. Legionella pneumophila (Lp) can cause fatal infection, however, such changes have not been investigated in legionellosis. Here, we evaluated the microbiome of the lungs, blood, liver, and small intestine content in Lp-infected guinea pigs.MethodsWe used a culture-independent method by analysing the conserved 16S rDNA sequences of bacteria from the organs of guinea pigs infected with legionellosis. Bacterial DNA was also identified through bacterial probe-fluorescence in situ hybridisation (BP-FISH). Bacterial entry from the intestinal lumen into the submucosa was examined via ultrastructural visualisation.ResultsAnoxybacillus kestanbolensis, Geobacillus vulcani, and other bacteria were identified in the small intestine content of healthy guinea pigs but not in other tissues. However, in Lp-infected guinea pigs, DNA from these bacteria was detected in the small intestine, lungs, blood, and liver tissues at 24 h and 48 h post-infection, indicating the possible translocation of gut bacteria to the remote tissues. This was validated through BP-FISH and ultrastructural visualisation. At 72 h post-infection, Pseudomonadota were the dominant gut bacteria, highlighting an imbalance in the gut microbiome.ConclusionInfection with the Legionella pneumophila serotype 1 disrupted the intestinal microbiota in a subset of guinea pigs during a 72-hour period post-infection, with possible translocation of gut-associated anaerobic bacteria to the lungs and liver based on the presence of genomic DNA detected in tissue from infected guinea pigs.

Establishment and validation of a simple and accurate qPCR detection method for Haemophilus parasuis

As an infectious disease that poses a significant threat to the rapidly growing pig breeding industry, the detection of Haemophilus parasuis (HPS) is often compromised by various interfering substances present in the test sample during quantitative real-time PCR (qPCR). The rapid detection of HPS is important for the isolation of infectious pigs and their treatment. We designed and optimized a rapid qPCR test to detect the INFB gene of HPS in clinical and environmental samples on pig farms. The method was evaluated for its specificity, sensitivity, repeatability, anti-interference capability, and its ability to detect HPS in clinical samples. The results indicated that the method was specific for the detection of HPS when evaluated against pathogens and intestinal probiotics found in pig farms. By using a seven-fold dilution series of the recombinant plasmid DNA in triplicate, it was determined that the lowest limit of detection (LOD) for this method was less than 10 copies/µL. The results of inter-batch and intra-batch repeatability tests showed that the coefficient of variation (CV) was consistently below 1%. Furthermore, the impact of 14 endogenous and exogenous interfering substances on the Ct values detected by the HPS qPCR was found to be less than 5% when compared to the Ct values obtained in the absence of interfering substances. A total of 248 clinical samples were analyzed using the HPS qPCR, commercial kits, and corresponding national standards, yielding positive rates of 9.27%, 6.05%, and 9.27%, respectively. Notably, the positive and negative percent agreement between the detection method developed in this research and the national standard was 100%. These findings demonstrate that the established detection method is suitable for epidemiological research on HPS and for diagnosing clinical samples containing interfering substances, thereby providing essential technical support for the prevention and control of HPS.

Can pigs add another “P” to the PPR? Serological evidence of frequent Peste des petits ruminants infections in pigs in Nigeria

To achieve the global eradication of Peste des petits ruminants (PPR), the epidemiological role of atypical hosts must be fully understood. Among domestic animals, pigs are, until now, the only species that has proven to fulfil criteria relevant for hosts to act as disease reservoir. This entails the susceptibility to infection via contact with infected animals as well as the shedding of infectious virus, resulting in new infections. However, these features have been observed only in infection experiments, lacking information from the field. In this study, for the first time, we provide evidence for frequent PPR virus exposure in pigs, detected in Nigeria. The prevailing husbandry systems targeted for sampling entailed predominantly free roaming pigs and small ruminants. The sampling area was selected on the basis of the occurrence of endemic PPR in small ruminants in recent years. Sera from 183 small ruminants and 495 pigs were analysed. The 25.68% apparent seroprevalence (95% CI 19.5–32.7 at the population level) observed in small ruminants matched values detected in Nigeria. The apparent seroprevalence in pigs of 4.24% (95% CI 2.6–6.5 at the population level) distributed across Nigeria provides evidence that PPR infections in pigs are not rare events. The ability of swine populations to propagate and maintain autonomous PPR infections over time remains to be clarified at this stage. Countries engaged in PPR eradication with substantial pig populations under extensive husbandry practices, including contact with small ruminants, should, however, consider surveillance strategies that address this possibly problematic interspecies interaction.

Serological survey of antibodies against Toxoplasma gondii and Neospora caninum in pigs from various regions of Poland

BackgroundPigs are prone to infections with several protozoa species. Although infection with Toxoplasma gondii rarely results in clinical symptoms in pigs, consuming pork-containing cysts represents a potential threat to human health, especially in immunocompromised individuals, pregnant women, and fetuses. It is estimated that around 2 billion people are infected with Toxoplasma gondii worldwide, making toxoplasmosis one of the most damaging zoonoses. Due to the coincidence of several factors, the meat from infected pigs can, however, frequently reach the consumer. In cattle, infection with Neospora caninum can cause considerable economic losses. The consequences of this infection for pigs remain unclear. However, infection in sows was linked with the development of some clinical signs, and transplacental transmission of the parasite was observed. Therefore, it should be considered a potential threat to pigs’ health. Due to the above reasons, the data regarding the epidemiology of the mentioned parasites seems desirable. Since Poland represents one of the major pig producers in the European Union, and pork is the most commonly consumed type of meat, the present study aimed to determine the seroprevalence of Toxoplasma gondii and Neospora caninum in the Polish pig population. 1034 serum samples were collected from 16 commercial farms localised in 9 different provinces (voivodeships) of Poland from pigs belonging to the following age categories: piglets (259), weaners (220), fatteners (243), gilts (70), and sows (242) were subjected to ELISA assay with the use of commercially available kits.ResultsThe overall seroprevalence of Toxoplasma gondii was 11.3% (117/1034), and it was significantly higher in sows compared to other age categories (28.1%; p < 0.05). Regarding the province of Poland, the highest proportion of seropositive pigs was found in Kujawsko-Pomorskie and Podlaskie; meanwhile, in Łódzkie, Pomorskie, and Warmińsko-Mazurskie observed seroprevalence was 0%. Among tested samples, only one (1/1034; 0.097%) was positive for Neospora caninum antibodies, and it was collected from gilt maintained on the farm in Zachodniopomorskie.ConclusionsThis study updates the data on Toxoplasma gondii epidemiology in pigs reared in Poland, showing relative stability in the infection with this parasite. It also provides the first data on Neospora caninum circulation in the Polish pig population.

Genetic characterization of porcine parainfluenza virus 1 (PPIV-1) in pig farms: first report of PPIV-1 in Thailand and Myanmar.

Porcine parainfluenza virus 1 (PPIV-1) is a paramyxovirus causing respiratory infections in pigs and has been reported worldwide. In this study, we conducted a cross-sectional survey of PPIV-1 in pig farms in Thailand and Myanmar from January 2022 to December 2023. Nasal swab samples from pigs in Thailand (n = 1,042) and Myanmar (n = 449) were collected from clinically healthy pigs and pigs with respiratory signs. PPIV-1 detection was carried out using the L gene-specific RT-PCR assay. Our results showed that 3.65% (38/1042) and 7.57% (34/449) were positive for PPIV-1 in Thailand and Myanmar, respectively. The viruses (n = 15) were subjected to whole genome sequencing (n = 4) and F and HN gene sequencing (n = 11). Genetic and phylogenetic analyses showed that Thai PPIV-1 (n = 7) was grouped into PPIV-1 lineage II (American lineage) and closely related to American and Chinese strains. On the other hand, one Thai PPIV-1 strain (n = 1) and Myanmar PPIV-1 (n = 7) belonged to lineage I (European lineage) and was closely related to European, Hong Kong (China), and South Korean strains. Our findings suggest that PPIV-1s from both lineages (I and II) are circulating in pigs in Thailand, and PPIV-1 of lineage I is circulating in pigs in Myanmar, suggesting high genetic diversity of PPIV-1 in the Southeast Asia region. This study is the first to report whole-genome sequences of PPIV-1 from pigs in Thailand and Myanmar. Our result provided insights and information about the current disease status and genetic diversity of PPIV-1 in pig farms, which will benefit further animal disease surveillance, prevention, and control.

An attenuated African swine fever virus expressing the E2 glycoprotein of classical swine fever virus protects pigs against challenge of both viruses

African swine fever (ASF) and classical swine fever (CSF) are highly contagious diseases with high morbidity and mortality rates resulting in an enormous impact on the global pig industry. A bivalent vaccine that simultaneously protects against both ASF and CSF is highly desirable. We previously developed a seven-gene-deleted African swine fever virus (ASFV) attenuated vaccine candidate (HLJ/18-7GD) that provides complete protection against homologous strains. Herein, we constructed a recombinant virus HLJ/18-7GD-E2 by inserting the classical swine fever virus (CSFV) E2 gene into the HLJ/18-7GD via homologous recombination. After continuous in vitro passaging, Western blotting analysis showed that the E2 gene was expressed and stably maintained within the ASFV genome. Next, the immunogenicity and protective efficacy of the recombinant HLJ/18-7GD-E2 virus was evaluated in pigs. The results revealed that a single dose of 106 TCID50 of HLJ/18-7GD-E2 induced an efficient immune response and provided complete protection against lethal challenges with ASFV or CSFV. These results demonstrate that recombinant ASFV expressing the CSFV E2 protein has potential as a bivalent live attenuated vaccine, providing solid protection against ASFV and CSFV infection in pigs.

Identification and characterization of Streptococcus suis strains isolated from eastern China Swine Farms, 2021–2023

The Streptococcus suis (S. suis) is an important zoonotic pathogen that causes streptococcal disease in pigs and poses a threat to humans. This study provides an understanding of the prevalence of S.suis in eastern China and provides guidance for clinical prophylaxis. From 2021 to 2023, a total of 143 strains of S. suis were isolated from 1642 lung tissue and nasal swabs from healthy and suspected infected pigs in Shandong Province, China, using the Phenotypic tests and PCR technique. The isolates were then tested for serotype, virulence-related genes, and resistance genes. Among the 143 isolates, type 2 was the predominant serotype with 98 isolates (98/143, 68.5%), followed by type 5 with 22 isolates (22/143, 15.3%), type 4 with 6 isolates (6/143, 4.2%), type 19 with 4 isolates (4/143, 2.8%) and type 21 with 5 isolates (5/143, 3.5%), respectively. A minimum of 78.3% of the strains exhibited the presence of virulence-related genes including pgda, dlta, mann, fbps, orf2, and sspa, whereas the virulence-associated genes Sum, Sly, and Salkr are not widely prevalent. For the detection of resistance genes, it was found that the tetO gene had a high detection rate of 70.1% (101/143), whereas neither the pbp2b gene nor the cat1 and cat2 genes were detected. Antimicrobial susceptibility testing revealed that 96.5% (138/143) of the isolates exhibited multidrug resistance (MDR). And polypeptide B was found to be tolerated by 125 of the 143 strains (87.4%). Although we did not detect the β-lactam resistance gene in any of the 143 strains, an average of 39.2% of the strains were resistant to β-lactam antibiotics. The results of the current study is thought it may be help to understand the prevalence of S. suis and provide important insights into treatment and prevention.

Evaluation of a nanoparticle influenza vaccine in the pig model.

Evaluation of a nanoparticle influenza vaccine in the pig model.

Nano-coating with silicon dioxide to reduce the occurrence of bacterial contamination in a pig abattoir drinking system.

A recently discovered source for infection of slaughter pigs, and thus entry for bacteria into the food chain, is the installed drinking equipment in lairage pens of pig abattoirs. To mitigate this, nano-coating of stainless steel, currently used in human medicine fields as well as in other parts of the food chain, appears as promising technology. In this study, silicon dioxide nano-coating was applied to six drinkers and installed for one and three months in a lairage of a pig abattoir, while results were compared with those of drinkers that had not been nano-coated. Laboratory examination of eight sample types related to the drinkers was conducted for total aerobic plate count, Enterobacteriaceae count, Pseudomonas spp. count, Salmonella presence, pathogenic Yersinia enterocolitica presence, Listeria monocytogenes presence and methicillin-resistant Staphylococcus aureus presence. The nipple drinker, which the pigs take into their mouth for drinking, was then examined using scanning electron microscopy and elemental analysis. The nano-coating did not produce statistically significant reductions in the loads or presence of these bacteria compared to the same but uncoated drinking equipment used under the same conditions. Further studies should focus on the implementation of combined methods, such as nano-coating and sanitary treatment, as well as modifications to the coating itself, to produce meaningful reductions of the bacterial loads on/in abattoir lairage drinking equipment.

Field Investigation Evaluating the Efficacy of Porcine Reproductive and Respiratory Syndrome Virus Type 2 (PRRSV-2) Modified Live Vaccines in Nursery Pigs Exposed to Multiple Heterologous PRRSV Strains.

This study was conducted to evaluate the protective efficacy of modified live vaccines (MLVs) against porcine reproductive and respiratory syndrome (PRRS) in nursery pigs in a worst case scenario where MLV does not match the genetic profile of the field isolate, different MLVs are used for sows and piglets, and piglets are naturally exposed to genetically distinct heterologous PRRS virus (PRRSV) isolates. We divided 76,075, 2-week-old piglets from a seropositive sow herd vaccinated with US1-MLV into four groups. US1-MLV, US2-MLV, and US3-MLV groups were vaccinated with PRRSV-2 MLV including Ingelvac® PRRS MLV (Boehringer Ingelheim, Ingelheim am Rhein, Germany), HP-PRRSV-2 based MLV (Harbin Veterinary Research Institute, CAAS, Harbin, China), and Prime Pac® PRRS (MSD Animal Health, Rahway, NJ, USA), respectively. The NonVac group was left unvaccinated. At 0, 14, 28, and 56 days post-vaccination (DPV), sera were assayed for the presence of PRRSV-specific antibodies using ELISA and serum neutralization (SN), and PRRSV RNA using PCR. Average daily gain (ADG) and survival rates were compared between treatment groups. The results demonstrated vaccinated groups significantly improved in ADG compared to the non-vaccinated control group. Only US1-MLV and US3-MLV were able to significantly reduce mortality associated with field PRRSV infection in nursery pigs. Pigs vaccinated with US3-MLV displayed significantly lower mortality and higher ADG compared to all other groups. Field isolates were isolated and genetically compared to all three MLV vaccines at the start of the trial. The MLV with closest genetic similarity to the field isolate was US2-MLV by ORF5 gene comparison. This provided the lowest protection judging by ADG improvement and mortality reduction, as compared to US1-MLV and US3-MLV. Separately, strains of Thai PRRSV-2 isolates collected in 2017, 2019, and 2020 in the study area were investigated for evolutionary changes. Over time, we observed a shift in PRRSV-2 isolates from lineage 8.7 to lineage 1. The field isolates found shared 82.59-84.42%, 83.75-85.74%, and 84.25-85.90% nucleotide identity with the US1-MLV, US3-MLV and US2-MLV based vaccine, respectively. Our findings suggest genetic similarity between field viruses and vaccine strains should not be used as a predictor of field performance. We found that zootechnical performance of piglets was best in US3-MLV, despite sows being treated with a different vaccine The results also support that different MLVs can be used at different stages of production. Finally, we concluded that the shift from lineage 8.7 to lineage 1 was due to shifts in the worldwide prevalence of PRRSV isolates during that period of time and not due to vaccine recombination between isolates. Overall, MLV vaccine selection should be based on production performance and safety profile.

Paeoniflorin Inhibits Porcine Circovirus Type 2 Replication by Inhibiting Autophagy and Targeting AKT/mTOR Signaling.

Porcine circovirus type 2 (PCV2) is an important pathogen that leads to great economic losses to the swine industry. Paeoniflorin (PF), a novel plant extract, has been reported to have antiviral properties. However, the role of paeoniflorin in regulating PCV2 replication remains unclear. Here, we used the CCK8 assay to demonstrate that PF within safe concentrations (0-275 mM) significantly inhibits PCV2 replication in a dose-dependent manner in porcine kidney cells. Subsequently, comparative transcriptome and functional verification revealed that PF probably inherits PCV2 replication via targeting AKT/mTOR signaling. Further experimental data show that the AKT/mTOR signaling pathway is highly relevant to autophagy. Thus, experimental data from Western blot, qPCR, and the indirect immunofluorescence test indicate that PF inhibits PCV2 replication by inhibiting autophagy by targeting the AKT/mTOR signaling pathway. Together, our results provide insight into the mechanism of paeoniflorin in regulating PCV2 replication and offer new ideas for the treatment of PCV2 infection in pigs.

Characterizing risk factors for infection of Mycobacterium bovis between wild pigs and domestic cattle from an outbreak response — California, 1961–1967

Characterizing risk factors for infection of Mycobacterium bovis between wild pigs and domestic cattle from an outbreak response — California, 1961–1967

Antiviral mechanism of Fuzhengjiedu San against porcine reproductive and respiratory syndrome virus.

Antiviral mechanism of Fuzhengjiedu San against porcine reproductive and respiratory syndrome virus.

Antiviral effect of pinostrobin, a bioactive constituent of Boesenbergia rotunda, against porcine epidemic diarrhea virus.

Antiviral effect of pinostrobin, a bioactive constituent of Boesenbergia rotunda, against porcine epidemic diarrhea virus.

Serologic differentiation between wild-type and cell-adapted African swine fever virus infections: A novel DIVA strategy using the MGF100-1L protein.

Serologic differentiation between wild-type and cell-adapted African swine fever virus infections: A novel DIVA strategy using the MGF100-1L protein.

Neospora caninum in pigs and pig farmers in India: Examining the prevalence, immunodominant antigens and associated risk factors.

Neospora caninum in pigs and pig farmers in India: Examining the prevalence, immunodominant antigens and associated risk factors.

Evaluation of the Dose of African Swine Fever Virus Required to Establish Infection in Pigs Following Oral Uptake.

African swine fever virus (ASFV) is known to be very stable within a protein-rich environment and indirect virus transmission can be mediated via oral uptake of different materials. However, experimental studies in pigs have shown that infection by ASFV via the oral route can be difficult to establish. Currently, there is a lack of studies using strict oral inoculations of pigs with different doses of ASFV. Therefore, we aimed to determine the dose of a European genotype II ASFV that is required to establish infection of pigs by the oral route. In this study, 24 pigs were divided into four groups of six. Three of the groups were fed with a low, medium or high dose of the ASFV POL/2015/Podlaskie virus. The pigs in the fourth group served as positive controls and were inoculated intranasally, just once, using the low dose of the virus. All the pigs inoculated intranasally with ASFV succumbed to the infection, while only three of the six pigs that were fed the high dose of the virus became infected. None of the 12 pigs that were fed with either the medium or low dose of the virus became infected, despite receiving up to thirteen doses each. In two of the pigs infected by intranasal inoculation, the presence of a variant form of the ASFV genome was detected. The results obtained in this study underline that ASFV infection is more difficult to establish via the oral route when compared to the intranasal route. The high dose needed in order to establish oral infection could have implications for future strategies using baited vaccines containing infectious live-attenuated ASFV.

ОЦЕНКА ИММУННОГО СТАТУСА МОЛОДНЯКА СВИНЕЙ ПРИ МИКОПЛАЗМЕННОЙ ИНФЕКЦИИ

Pig farming still suffers significant economic losses due to infection of animals with mycoplasmas. The pathogenic effect of these bacteria on the body of pigs is especially pronounced in young animals. The purpose of research is to study the nature of the impact of mycoplasma infection on the immune status of piglets. To assess the epizootological state of the complex regarding mycoplasmosis, random blood tests were carried out from all technological groups of pigs using the RNG reaction and determining the percentage of infection. Morbidity was determined by the number of animals identified with clinical signs of the disease among those infected, and mortality was determined by the number of dead animals among those infected with mycoplasmosis. Blood protein fractions were determined in piglets using an ERBA-XL100 biochemical analyzer. Determination of T-lymphocytes was done by the method of spontaneous rosette formation with sheep erythrocytes (E-ROCK). Determination of B cells was carried out in the complementary rosette formation reaction (EAC-ROCK). It was established that the infection of pigs with mycoplasmosis in different groups at the complex ranged from 24.2–65.7 %, while the highest percentage of morbidity (26.8 %) and mortality (18.6 %) of individuals was observed among piglets in growing. The negative impact of mycoplasma infection on the immune status of young pigs was manifested by a decrease in total protein (by 13.5 %) and gamma globulin fraction (by 17.8 %) in the blood serum of sick piglets compared to healthy ones. The impact of pathogenic mycoplasmas on the cellular link of the immune-competent system of the body of sick piglets was manifested by a decrease in their T-lymphocytes by 11 %, and B-lymphocytes by 21.4 % compared to healthy animals.

Lineage 7 Porcine Reproductive and Respiratory Syndrome Vaccine Demonstrates Cross-Protection Against Lineage 1 and Lineage 3 Strains.

Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) has a major impact on swine productivity. Modified-live vaccines (MLVs) are used to aid in control. We investigated the cross-protection provided by a lineage 7 PRRSV MLV against a lineage 1 isolate under laboratory conditions and a lineage 3 challenge under field conditions in Taiwan. Methods: In the first study, thirty PRRS antibody-negative conventional piglets were vaccinated via the intramuscular (IM) or the intradermal (ID) route, with the control group receiving a placebo. Four weeks after immunization, all groups were challenged with a Taiwanese lineage 1 strain. The standard protocol for detection of reversion to virulence was applied to the vaccine strain in the second study, using sixteen specific pathogen-free piglets. In the third study, on an infected pig farm in Taiwan (lineage 3 strain), three hundred piglets were randomly selected and divided into three groups, each injected with either the PrimePac® PRRS vaccine via the IM or the ID route, or a placebo. Results: In the first study, both vaccinated groups demonstrated reduced viraemia compared to the control group. The second study demonstrated that the MLV strain was stable. In the third study, piglet mortality, average daily weight gain, and pig stunting rate were significantly improved in the vaccinated groups compared to the control group. Conclusions: PrimePac® PRRS is safe to use in the field in the face of a heterologous challenge, successfully providing cross-protection against contemporary lineage 1 and lineage 3 PRRSV strains from Taiwan.

An Efficient, Organic Solvent-Free Method for Extraction and Concentration of Hepatitis E Virus from Pig Liver

Abstract The presence of the hepatitis E virus (HEV) in pork products, particularly in pig liver has been frequently described. However, a standardized method is not still available for the detection of HEV in foods, particularly in those difficult food matrixes such as pig meat and pork products. The aim of this study was to design, optimize and evaluate a new method of food-separation and virus concentration for HEV in pig liver samples. This method is based on organic flocculation and avoids the use of organic solvents. The virus recovery rates and analytical sensitivity of the method using murine norovirus MNV-1 as a surrogate were 73.6–82.2% and at least 1 × 103 TCID50 per g of liver in 100% of the replicates, respectively. Furthermore, this new methodology was validated by testing the presence of HEV RNA in naturally infected pig liver samples, comparing it with two other commonly used concentration methods. The new extraction method run satisfactory in comparison with the two reference methods; statistically equivalent (p &lt; 0.05) to one of the methods used while presented statistically significant better results (p &lt; 0.05) compared to the second method. Consequently, our results indicate that the new extraction method can be an adequate cost-effective and ecologically friendly alternative for the food separation and concentration of HEV RNA in pig liver samples.