Porcine Reproductive Respiratory Syndrome Research Articles

28 On-Farm Rapid Test to Assess Immunological Health of Young Pigs

Abstract Immunological competence is important for young pig survivability. A rapid on-farm test of immunological status may be a tool to help with early identification of sick animals. A new immunological test uses gold nanoparticle technology (D2Dx) to detect changes in serum proteins, particularly IgG and was evaluated as a potential on-farm measure of immunological health of pigs born during a farm level Porcine Respiratory Reproductive Syndrome (PRRS) outbreak. Up to three piglets from each litter in 2 farrowing groups (28 days apart) were selected for serial blood sampling and monitoring of body weight. Group 1 (n = 13 sows) experienced the PRRS outbreak approximately 14 days before farrowing and Group 2 (n = 15) approximately 40 days before farrowing. Attempts were made to select one piglet from each of 3 general categories [small (< 1.0 kg), average (1.1 – 1.6 kg), heavy (>1.6 kg)] from each litter. Serum samples were collected at day 2 and 15 of age from each piglet and serum IgG concentration and D2Dx ratio were assessed. Serum immunocrit at day 2 was also completed. Daily animal care of piglets and sows followed standard barn protocols. No creep feed was provided, sows were fed ad libitum, and cross-fostering was limited. Stillborn rate and preweaning death loss was approximately 70% in Group 1 and 35% in Group 2. Birth weight was similar between Group 1 and 2 litters (1.4 ± 0.3 kg). However, body weight gain to day 15 was 1.7 ± 0.95 kg and 2.7 ± 1.1 kg for piglets from Group 1 and 2, respectively, which may be due to timing of the PRRS outbreak. The D2Dx ratio declined from day 2 to 15 (0.029 vs -0.002) in both groups and was significantly reduced in Group 2 pigs (P < 0.001). A lower ratio suggests a stronger type 2 immune response and has been associated with decreased overall immunity in cattle, humans, and rodents. The D2Dx ratio was negatively correlated (r = -0.58) with BW gain in Group 1 pigs and positively correlated (r = 0.36) with gain in Group 2 pigs. Both immunocrit (day 2) and IgG (d15) were greater in Group 1 pigs than Group 2 (P < 0.01). There was a no relationship between birth weight and day 2 serum immunocrit (R2 = 0.06) or day 2 D2Dx (R2 = 0.01). There was no relationship between serum IgG and D2Dx at d15. The PRRS disease activity impacts immunocrit and serum IgG measures in the neonatal pig. The D2Dx ratio was not strongly related to piglet immunological status under disease conditions; however, the stronger type 2 immune response may be reflective of positive changes in piglet immune function and the response to maternal PRRS antibodies in milk.

Reproductive and respiratory syndrome of pigs in pig breeding enterprises (review)

Porcine Reproductive Respiratory Syndrome (PRRS) causes significant economic losses in pig production around the world. The virus is highly contagious and spreads both by aerosol and with all biological secretions, and the disease itself is characterized by fever, weight loss and abortion of fetuses. This swine disease is relatively new, for the first-time clinical signs were described in 1986, and in 1991 the pathogen was isolated. The main problems hindering the fight against the virus currently remain: the insufficient effectiveness of existing vaccines, the high genetic variability of the pathogen, the ability of PRRSV to suppress the host's immune system, and long-term virus carriers in recovered animals. The review on porcine reproductive and respiratory syndrome presents data on the genetic diversity of virus strains that differ in the degree of virulence and pathogenicity, sources of infection and ways of transmission of the virus. The article also contains data on the spread of PRRS in the world and in Russia. It is noted that the disease has been reported in many swine-producing countries, where, after a phase of active spread, the disease became endemic. And in 2021, according to the to the International Epizootic Bureau (OIE), outbreaks of PRRSV were detected in domestic pigs in Ecuador, Uruguay, Nepal, China, Bahrain, Switzerland and Ukraine, as well as in wild boars in Bahrain, Switzerland and Ukraine. According to the published data of monitoring studies conducted in the period from 2012 to 2017, only single territorially limited outbreaks were detected in Russia. Earlier studies indicate a wide distribution of the PRRS pathogen in Russia. The effectiveness of various variants of live and inactivated vaccines is described in detail, and it has been established that live attenuated vaccines are most effective against PRRS. The features of the protection of the territory of a number of states (Norway, Sweden, Finland, Switzerland) from the introduction of the pathogen, which by now remain free from PRRS, as well as the experience of Hungary in the eradication of the disease, are analyzed. All preventive measures in the pig farm in case of detection of the virus should include general, veterinary-sanitary and special measures, for diagnosis it is better to use modern RT-PCR test systems that allow distinguishing PRRS genotypes, in combination with serological tests, and for vaccination choose a registered and approved vaccine based on the genetic characteristics of the pathogen circulating in the area.

Development of a farm-specific real-time quantitative RT-PCR assay for the detection and discrimination of wild-type porcine reproductive respiratory syndrome virus and the vaccine strain in a farm under eradication.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases of swine causing severe economic losses worldwide, therefore intensive efforts are taken to eliminate PRRS virus (PRRSV) from infected herds for complete eradication. The most efficient, fastest but at the same time the most expensive eradication method is depopulation-repopulation. In order to reduce costs, a number of farms prefer to perform their eradication process with continuous production using modified live vaccine (MLV) immunisation. However, the commercial PRRSV RT-PCR kits do not have the capacity to discriminate infected from vaccinated animals. In this paper, we describe a simple discriminatory duplex TaqMan RT-PCR assay based on common forward and reverse primers, as well as two differently labelled MLV- and wild-type PRRSV-specific probes. The discriminatory PCR test we designed is a fast and efficacious method for processing large quantities of samples. The assay is cheap, flexible, easy to apply in different herds using different MLVs, but should be checked, and can be modified based on the sequence data obtained during the permanent monitoring examinations. Owing to its simplicity the test can serve as a significant complementary assay for PRRS control and elimination/eradication.

Detection of Swine Influenza A and Porcine Reproductive and Respiratory Syndrome Viruses in Nasopharynx-Associated Lymphoid Tissue

Porcine respiratory disease complex, which is caused by a combination of pathogens, including swine influenza A virus (SIV) and porcine reproductive respiratory syndrome virus (PRRSV), results in significant economic losses in pig production systems. Nasopharynx-associated lymphoid tissue (NALT) plays an important role in the uptake of pathogens and defence of the nasal mucosa in rodents and humans. We characterized NALT M cells in pigs and detected SIV antigen and PRRSV nucleic acid in NALT using histopathological, immunohistochemical and in-situ hybridization analyses. All SIV- and PRRSV-positive cases examined had suppurative nasopharyngitis and pneumonia. M cells were detected by immunohistochemistry and the distribution of M cells showed an increase in the middle section of NALT. SIV antigen was detected in M cells and PRRSV nucleic acid was demonstrated in the cytoplasm of macrophages in NALT. We believe that SIV and PRRSV infection in the upper respiratory tract induces local immunosuppression and these results confirm that swine NALT is a location for virus replication and may be strongly associated with the development of pneumonia in pigs.

РЕПРОДУКТИВНО-РЕСПИРАТОРНЫЙ СИНДРОМ СВИНЕЙ: СИТУАЦИЯ В РОССИИ

This review presents data on the Porcine Reproductive Respiratory Syndrome. The genetic diversity of pathogens in the Russian Federation and their biological properties are considered. The current epizootological situation around the world and in Russia in particular.

Common Disease Symptoms and Occurrence of Porcine Reproductive Respiratory Syndrome and Hog Cholera In Native Pigs Raised In Pampanga, Philippines

Common Disease Symptoms and Occurrence of Porcine Reproductive Respiratory Syndrome and Hog Cholera In Native Pigs Raised In Pampanga, Philippines

PRRS: the most costly disease of pig production

Porcine reproductive respiratory syndrome virus replicates in monocytes, compromising the pig's immune system and making them vulnerable to other endemic diseases; this is the most economically impactful aspect of PRRS.

Dynamics of a delayed SIR model for the transmission of PRRSV among a swine population

The objective of this paper is to propose a delayed susceptible-infectious-recovered (SIR) model for the transmission of porcine reproductive respiratory syndrome virus (PRRSV) among a swine population, including the latent period delay of the virus and the time delay due to the period the infectious swines need to recover. By taking different combinations of the two delays as the bifurcation parameter, local stability of the disease-present equilibrium and the existence of Hopf bifurcation are analyzed. Sufficient conditions for global stability of the disease-present equilibrium are derived by constructing a suitable Lyapunov function. Directly afterwards, properties of the Hopf bifurcation such as direction and stability are studied with the aid of the normal form theory and center manifold theorem. Finally, numerical simulations are presented to justify the validity of the derived theoretical results.

Porcine Circovirus Type 2 Suppresses IL-12p40 Induction via Capsid/gC1qR-Mediated MicroRNAs and Signalings.

Porcine circovirus (PCV) type 2 (PCV2), an immunosuppression pathogen, is often found to increase the risk of other pathogenic infections. Yet the relative immune mechanisms determining the susceptibility of PCV2-infected animals remain unclear. In this study, we confirmed that PCV2 infection suppressed IL-12p40 expression and host Th1 immune response, leading to a weakened pathogenic clearance upon porcine reproductive respiratory syndrome virus (PRRSV) or Haemophilus parasuis infection. PCV2 infection suppressed pathogens, LPS/IFN-γ, or LPS/R848-induced IL-12p40 expression in porcine alveolar macrophages. PCV2 capsid (Cap) was the major component to suppress IL-12p40 induction by LPS/IFN-γ, LPS/R848, PRRSV, or H. parasuis Either wild-type PCV2 or mutants PCV2-replicase 1 and PCV type 1-Cap2, which contained PCV2 Cap, significantly decreased IL-12p40 levels and increased the replication of PRRSV and H. parasuis in the lung tissues relative to mock or PCV type 1 infection. gC1qR, a Cap binding protein, was not involved in IL-12p40 induction but mediated the inhibitory effect of PCV2 Cap on IL-12p40 induction. PCV2 also activated PI3K/Akt1 and p38 MAPK signalings to inhibit IL-12p40 expression via inhibition of NF-κB p65 binding to il12B promoter and upregulation of miR-23a and miR-29b. Knockdown of Akt1 and p38 MAPK downregulated miR-23a and miR-29b and increased IL-12p40 expression. Inhibition of miR-23a and miR-29b attenuated the inhibitory effect of PCV2 on IL-12p40 induction, resulting in an increased IL-12p40 expression and Th1 cell population and reduced susceptibility to PRRSV or H. parasuis Taken together, these results demonstrate that PCV2 infection suppresses IL-12p40 expression to lower host Th1 immunity to increase the risk of other pathogenic infection via gC1qR-mediated PI3K/Akt1 and p38 MAPK signaling activation.

OptisampleTM: Open web-based application to optimize sampling strategies for active surveillance activities at the herd level illustrated using Porcine Respiratory Reproductive Syndrome (PRRS).

Porcine reproductive and respiratory syndrome virus (PRRSv) infection causes a devastating economic impact to the swine industry. Active surveillance is routinely conducted in many swine herds to demonstrate freedom from PRRSv infection. The design of efficient active surveillance sampling schemes is challenging because optimum surveillance strategies may differ depending on infection status, herd structure, management, or resources for conducting sampling. Here, we present an open web-based application, named ‘OptisampleTM’, designed to optimize herd sampling strategies to substantiate freedom of infection considering also costs of testing. In addition to herd size, expected prevalence, test sensitivity, and desired level of confidence, the model takes into account the presumed risk of pathogen introduction between samples, the structure of the herd, and the process to select the samples over time. We illustrate the functionality and capacity of ‘OptisampleTM’ through its application to active surveillance of PRRSv in hypothetical swine herds under disparate epidemiological situations. Diverse sampling schemes were simulated and compared for each herd to identify effective strategies at low costs. The model results show that to demonstrate freedom from disease, it is important to consider both the epidemiological situation of the herd and the sample selected. The approach illustrated here for PRRSv may be easily extended to other animal disease surveillance systems using the web-based application available at http://stemma.ahc.umn.edu/optisample.

Polymerase cross-linking spiral reaction (PCLSR) for detection of African swine fever virus (ASFV) in pigs and wild boars

The study reports the development of a polymerase cross-linking spiral reaction (PCLSR) for the detection of African swine fever virus (ASFV) DNA in blood collected from infected pigs and wild boars. The method uses 3 specifically designed primers. Two outer-spiral primers comprising of 3′ sequences complementary to ASFV p72 gene sequence and 5′end sequences complementary to exogenous gene of black widow alpha-latrotoxin as well as additional ASFV specific cross-linking primer. The method is specific exclusively to ASFV DNA without cross-reactions with cDNA of classical swine fever virus (CSFV), porcine reproductive respiratory syndrome (PRRSV) or porcine epidemic diarrhea virus (PEDV). The sensitivity of this technique reached 7.2 × 102 copies per μl−1 of plasmid containing p72 gene. The PCLSR was conducted at 65 °C creating cross-linked complex structures. The results of PCLSR were visualized using SYBR Green I dye, gel electrophoresis while the reaction progress was traced using real-time PCR system that resulted in registration of fluorescent curves and melting peaks at 85.3 °C. The developed PCLSR was examined using blood or tissue samples collected from selected 17 ASF cases from infected wild boars and 3 outbreaks in pigs. Further tests have been also conducted using 55 tissue samples from 23 outbreaks and 22 cases. These results showed that PCLSR might be further used for preliminary and cost-effective detection and surveillance of ASFV.

Síndrome Reproductivo Respiratorio Porcino: Presentación en el Tiempo y Efecto sobre los Parámetros Productivos y Reproductivos

El objetivo del estudio fue evaluar la presentación del Síndrome Reproductivo Respiratorio Porcino (PRRS) en el tiempo y determinar el efecto que produce sobre las características productivas y reproductivas. Se evaluó el comportamiento productivo de 210 marranas Camborough 22, que parieron entre 2013 y 2015 en una granja porcina de Lima, Perú. Las características evaluadas fueron el promedio semanal/camada de lechones nacidos (NT), total de lechones nacidos vivos (NV), total de lechones nacidos muertos (NM), peso vivo de los lechones nacidos (PVLN), total de lechones destetados (LD), peso vivo de lechones destetados (PVLD), mortalidad de lechones al destete (MLD), peso vivo de lechones a los 70 días (PVL70) y mortalidad de lechones a los 70 días (ML70). El incremento de los NM superior a los límites normales de las gráficas de control duró 13 semanas, evidenciándose a partir de la semana 95 (cuarta semana octubre 2014) y se prolongó hasta la semana 108 (segunda semana febrero 2015). En el año de la presentación del PRRS, los NM, PVLN y ML70 se incrementaron en 2.3 veces, 6.8% y 13 veces, respectivamente (p<0.05), mientras que el NT, NV, LD, MLD y PVL70 disminuyeron en 16.4, 22.0, 20.5, 44.6 y 11.6%, respectivamente (p<0.05). La menor productividad redujo los ingresos por marrana/año hasta un 35.6%. El PRRS afectó los principales parámetros reproductivos y productivos evaluados hasta los 70 días de edad, generando pérdidas económicas.<br /><p> </p>

257 Effects of Porcine Reproductive Respiratory Syndrome (PRRS) status (stable vs. active) on the performance of weaned pigs when fed either a complex diet, a simple diet or a simple diet with lactose

257 Effects of Porcine Reproductive Respiratory Syndrome (PRRS) status (stable vs. active) on the performance of weaned pigs when fed either a complex diet, a simple diet or a simple diet with lactose

Matrine displayed antiviral activity in porcine alveolar macrophages co-infected by porcine reproductive and respiratory syndrome virus and porcine circovirus type 2

The co-infection of porcine reproductive respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) is quite common in clinical settings and no effective treatment to the co-infection is available. In this study, we established the porcine alveolar macrophages (PAM) cells model co-infected with PRRSV/PCV2 with modification in vitro, and investigated the antiviral activity of Matrine on this cell model and further evaluated the effect of Matrine on virus-induced TLR3,4/NF-κB/TNF-α pathway. The results demonstrated PAM cells inoculated with PRRSV followed by PCV2 2 h later enhanced PRRSV and PCV2 replications. Matrine treatment suppressed both PRRSV and PCV2 infection at 12 h post infection. Furthermore, PRRSV/PCV2 co- infection induced IκBα degradation and phosphorylation as well as the translocation of NF-κB from the cytoplasm to the nucleus indicating that PRRSV/PCV2 co-infection induced NF-κB activation. Matrine treatment significantly down-regulated the expression of TLR3, TLR4 and TNF-α although it, to some extent, suppressed p-IκBα expression, suggesting that TLR3,4/NF-κB/TNF-α pathway play an important role of Matrine in combating PRRSV/PCV2 co-infection. It is concluded that Matrine possesses activity against PRRSV/PCV2 co-infection in vitro and suppression of the TLR3,4/NF-κB/TNF-α pathway as an important underlying molecular mechanism. These findings warrant Matrine to be further explored for its antiviral activity in clinical settings.

축산물 중의 Polybrominated Diphenyl Ethers (PBDEs) 분석

Polybrominated diphenyl ethers (PBDEs) as flame-retardant additives have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally similar to PCBs and other polyhalogenated compounds. PBDEs are found in a variety of foods, and 95% of all human exposure to POPs comes from food. The major food sources are fish/seafood and dairy products. A number of studies have reported high levels of PBDEs in animals, increasing the public's concern over PBDE levels in animals. This study evaluates the relationship between the level of PBDEs according to piglet diseases. Salmonella spp. and Streptococcus are bacterial diseases. Porcine respiratory reproductive syndrome (PRRS) is a viral disease. The concentration of PBDEs in the piglet liver from viral diseases was higher than that from bacterial diseases. BDE-47 and BDE-99 were detected in most samples. More PBDEs were detected in the piglet liver from PRRS of North American type than from that of European type.

Molecular genetic analysis of genomes of porcine respiratory and reproductive syndrome viruses and porcine circovirus type 2 circulating on the territory of the Russian federation

A molecular genetic analysis of genomes of porcine reproductive respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV-2) circulating in the territory of the Russian Federation is given. The results of the study showed the presence of circulation of European genotypes of PRRSV strains that are similar to isolates found in France and Denmark from 1998 to 2001. We explained the homology of a fragment of one of the genes between the Russian isolates and the vaccine strain used in Porcilis PRRS (Intervet) vaccine, but this requires further study. Strains of the North American genotype of PRRS were not found. The PCV-2 genomes fall into three separate groups. One (genotype 2b) is formed by isolates in Malaysia, Brazil, Switzerland, China, Slovakia, the United Kingdom, and the United States, which were isolated during the period from 2004 to the present time. The second group consists of the field sequences of viruses isolated in 2000–2012 in Canada, the United States, China, and South Korea (genotype 2a). The third group is formed by highly pathogenic isolates evolved in 2013 in China (genotype 2c). The circulation of all three known genotypes of PCV-2-2a, 2b, and 2c-in the Russian Federation was shown.

Phylogenetic comparison of porcine circovirus type 2 (PCV2) and porcine reproductive respiratory syndrome virus (PRRSV) strains detected in domestic pigs until 2008 and in 2012 in Croatia.

BackgroundPorcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) have been present for the last 2 decades in Croatia, causing large economical losses in the pig production. The clinical features of the infections are mostly manifested by the development of respiratory problems, weight loss and poor growth performance, as well as reproductive failure in pregnant sows. Even though the infections are continuously recognized in some regions in Croatia, the heterogeneity of the detected viral strains from 2012 has not yet been investigated. The objective of this study was to compare virus strains of PCV2 and PRRSV detected until 2008 in Croatia with strains isolated in 2012 to gain a better epidemiological understanding of these two infections.ResultsPCV2 and PRRSV strains detected in 2012 in fattening pigs from regions where these two diseases have been previously described were compared to strains that have been detected in the same regions within the past two decades. The phylogenetic analysis revealed that the circulating PCV2 and PRRSV strains are distantly related to the previously described Croatian viral strains. However, when compared to known isolates from the GenBank a high genetic identity of PRRSV isolates with isolates from Hungary, Denmark and the Netherlands was found.ConclusionThe results of this study reveal that even though PCV2 and PRRSV are constantly present in the investigated regions in Croatia, the viral strains found in 2012 genetically differ from those detected in earlier years. This indicates that new entries into the pig population appeared with regard to both infections, probably as a result of pig trade.

Virulence and genotype-associated infectivity of interferon-treated macrophages by porcine reproductive and respiratory syndrome viruses

The polarization into M1 and M2 macrophages (MΦ) is essential to understand MΦ function. Consequently, the aim of this study was to determine the impact of IFN-γ (M1), IL-4 (M2) and IFN-β activation of MΦ on the susceptibility to genotype 1 and 2 porcine reproductive respiratory syndrome (PRRS) virus (PRRSV) strains varying in virulence. To this end, monocyte-derived MΦ were generated by culture during 72h and polarization was induced for another 24h by addition of IFN-γ, IL-4 or IFN-β. MΦ were infected with a collection of PRRSV isolates belonging to genotype 1 and genotype 2. Undifferentiated and M2 MΦ were highly susceptible to all PRRSV isolates. In contrast, M1 and IFN-β activated MΦ were resistant to low pathogenic genotype 1 PRRSV but not or only partially to genotype 2 PRRSV strains. Interestingly, highly virulent PRRSV isolates of both genotypes showed particularly high levels of infection compared with the prototype viruses in both M1 and IFN-β-treated MΦ (P<0.05). This was seen at the level of nucleocapsid expression, viral titres and virus-induced cell death. In conclusion, by using IFN-γ and IFN-β stimulated MΦ it is possible to discriminate between PRRSV varying in genotype and virulence. Genotype 2 PRRSV strains are more efficient at escaping the intrinsic antiviral effects induced by type I and II IFNs. Our in vitro model will help to identify viral genetic elements responsible for virulence, an information important not only to understand PRRS pathogenesis but also for a rational vaccine design. Our results also suggest that monocyte-derived MΦ can be used as a PRRSV infection model instead of alveolar MΦ, avoiding the killing of pigs.

Recombinant chimeric vaccine composed of PRRSV antigens and truncated Pseudomonas exotoxin A (PE-K13)

A Pseudomonas exotoxin (PE-KDEL)-based chimeric subunit vaccine system was recently developed using a reverse vaccinology technique. In this study, the plasmids containing PE-PRRS chimeric subunits were constructed that composed of porcine reproductive and respiratory syndrome virus (PRRSV) antigen moieties, a ligand moiety and a Pseudomonas exotoxin A deleted domain III (PE (ΔIII)), and a carboxyl terminal moiety that includes a polypeptide with amino acid sequence KDEL (K3). The PE-PRRS combination vaccine can effectively induce not only PRRSV-specific INF-γ cellular immunity but also a slow-reacting and complement-requiring type serum neutralizing antibody in pigs. In a specific pathogen free (SPF) pig challenge model, body temperature (colonic temperature), occurrence of PRRSV viremia, nasal excretions, gross and histopathological appearances of pneumonia, and serum antibody activity (IFA and SN) titers significantly differed between the immunized group and the control group. The survey showed that a 0.3mg/dose PE-PRRS vaccine formula conferred protection against PRRSV. A field trial of PE-PRRS vaccine was performed to study the immune response of pregnant sows after vaccination in a PRRSV persist farm. The RT-PCR analysis of viremia and serological titers showed that the PE-PRRS vaccine not only increased sow reproductive performance and evoked its immune response to PRRS viremia, it also activated maternal immune protections to prevent piglets from inflicting viremia. In conclusion, we developed a novel and effective PRRS cytotoxic T-cells (CTLs)-based vaccine containing Pseudomonas exotoxin (PE-KDEL) carrier in combination with PRRSV conserved epitopes against PRRS virus.

Oral Administration of EC-12 Increases the Baseline Gene Expression of Antiviral Cytokine Genes, IFN-γ and TNF-α, in Splenocytes and Mesenteric Lymph Node Cells of Weaning Piglets.

Weaning piglets are continuously exposed to various viruses. The antiviral effects of lactic acid bacteria (LAB) have been confirmed mainly in humans and mice, while few studies have been conducted in livestock. In this study, we evaluated the effect of oral administration of Enterococcus faecalis strain EC-12 (EC-12) on the gene expressions of antiviral cytokines in weaning piglets. Piglets were allocated to the EC-12-administered group (E group) and the no-treatment control group (C group). The small intestinal tissue, the mesenteric lymph node (MLN) cells and the splenocytes were collected from the piglets. The tissue and cells were co-cultured with a live vaccine of porcine reproductive respiratory syndrome virus, porcine epidemic diarrhea virus or EC-12. After the incubation, the gene expressions of IFN-γ and TNF-α in the tissue and cells were evaluated. The gene expressions of IFN-γ in the MLN cells and TNF-α in the splenocytes were significantly higher in the E group than in the C group. However, the increase in the gene expression of antiviral cytokines was observed independently of the antigen treatments. The results of the present study suggest that oral administration of EC-12 did not increase the response of immune cells to specific viral antigens but increased the baseline gene expression of antiviral cytokines.