Pathological and immunohistochemical assessment of the impact of three different strains of swine enteric coronaviruses in the intestinal barrier.

Swine enteric coronaviruses, such as porcine epidemic diarrhea virus (PEDV) or transmissible gastroenteritis virus (TGEV), have risen concern for the porcine industry and research community due to the increase in their virulence, their potential recombination capacity and the emergence of new variants. This in vivo study aims to compare the impact of three different strains of swine enteric coronaviruses [(two G1b (S-INDEL) PEDV strains and a recombinant TGEV-PEDV or Swine enteric coronavirus (SeCoV)] in the intestine of 3-weeks-old infected piglets, focusing on the pathology and main components of the intestinal barrier, including the number of goblet cells, and the expression of IgA as well as FoxP3, a regulatory T cell marker. Severity of lesions was evidenced in the three infected groups and was highly correlated with the viral load in feces and the frequency of viral antigen-positive cells. Furthermore, higher cellular death together with an increase in the expression of the FoxP3 marker was detected in the duodenum and jejunum of infected animals at 3 days post-infection. Our results highlight a recruitment of FoxP3+ cells in the small intestine of infected animals which may represent a response to the tissue damage caused by viral replication and cell death. Further studies should be addressed to determine the potential role of these cells during swine enteric coronavirus infections.

Phenotypic and genotypic antibiotic resistance patterns in Salmonella Typhimurium and its monophasic variant from pigs in southern Spain.

The high incidence of human salmonellosis and multi-drug resistant (MDR) strains of Salmonella Typhimurium (ST) is of concern to global public and animal health. Our research, by means of the broth microdilution method, evaluated the Minimum Inhibitory Concentration (MIC) distribution of 12 antimicrobials against a collection of 73 ST and mST and S. typhimurium monophasic variant 4,[5],12:i:- (mST) isolates from slaughtered pigs reared in extensive systems in southern Spain, and also 12 resistance-associated genes or antimicrobial resistance (AMR) determinants using qPCR. Our data revealed that 98.6% of strains were MDR, with resistance to cephalothin/tetracycline/sulfamethoxazole-trimethoprim/ampicillin/chloramphenicol being the most common pattern (55.6%). Regarding AMR determinants, the most significantly (p < 0.05) genes detected by qPCR were sul1 and aadA2 (89% of strains positive), aadA1 and dfrA12 (87.7%), and blaTEM and tet(B) (86.3% and 84.9%, respectively). Up to date information on ST antimicrobial resistance patterns is essential for epidemiological surveillance programs to support animal and public health. The high number of MDR isolates and variability regarding resistance determinants revealed in this study highlights the role of animals reared in extensive systems as a source of resistant Salmonella strains.

Time Series Transcriptomic Analysis of Bronchoalveolar Lavage Cells from Piglets Infected with Virulent or Low-Virulent Porcine Reproductive and Respiratory Syndrome Virus 1.

Porcine reproductive and respiratory syndrome virus (PRRSV) has evolved to escape the immune surveillance for a survival advantage leading to a strong modulation of host's immune responses and favoring secondary bacterial infections. However, limited data are available on how the immunological and transcriptional responses elicited by virulent and low-virulent PRRSV-1 strains are comparable and how they are conserved during the infection. To explore the kinetic transcriptional signature associated with the modulation of host immune response at lung level, a time-series transcriptomic analysis was performed in bronchoalveolar lavage cells upon experimental in vivo infection with two PRRSV-1 strains of different virulence, virulent subtype 3 Lena strain or the low-virulent subtype 1 3249 strain. The time-series analysis revealed overlapping patterns of dysregulated genes enriched in T-cell signaling pathways among both virulent and low-virulent strains, highlighting an upregulation of co-stimulatory and co-inhibitory immune checkpoints that were disclosed as Hub genes. On the other hand, virulent Lena infection induced an early and more marked "negative regulation of immune system process" with an overexpression of co-inhibitory receptors genes related to T-cell and NK cell functions, in association with more severe lung lesion, lung viral load, and BAL cell kinetics. These results underline a complex network of molecular mechanisms governing PRRSV-1 immunopathogenesis at lung level, revealing a pivotal role of co-inhibitory and co-stimulatory immune checkpoints in the pulmonary disease, which may have an impact on T-cell activation and related pathways. These immune checkpoints, together with the regulation of cytokine-signaling pathways, modulated in a virulence-dependent fashion, orchestrate an interplay among pro- and anti-inflammatory responses. IMPORTANCE Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the major threats to swine health and global production, causing substantial economic losses. We explore the mechanisms involved in the modulation of host immune response at lung level performing a time-series transcriptomic analysis upon experimental infection with two PRRSV-1 strains of different virulence. A complex network of molecular mechanisms was revealed to control the immunopathogenesis of PRRSV-1 infection, highlighting an interplay among pro- and anti-inflammatory responses as a potential mechanism to restrict inflammation-induced lung injury. Moreover, a pivotal role of co-inhibitory and co-stimulatory immune checkpoints was evidenced, which may lead to progressive dysfunction of T cells, impairing viral clearance and leading to persistent infection, favoring as well secondary bacterial infections or viral rebound. However, further studies should be conducted to evaluate the functional role of immune checkpoints in advanced stages of PRRSV infection and explore a possible T-cell exhaustion state.

The jigsaw of PRRSV virulence.

Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of the, probably, most economically important disease for the pig industry worldwide. This disease, characterised by producing reproductive failure in sows and respiratory problems in growing pigs, appeared in the late 1980s in the United States and Canada. Since its appearance, strains capable of producing higher mortality rates as well as greater severity in clinical signs and lesions than classical strains have been identified. However, since the first reports of these "virulent" PRRSV outbreaks, no homogeneity and consensus in their description have been established. Moreover, to the authors' knowledge, there is no published information related to the criteria that a PRRSV strain should fulfil to be considered as a "virulent" strain. In this review, we revise the terminology used and gather the information related to the main characteristics and differences in clinical signs, lesions, viral replication and tropism as well as immunological parameters between virulent and classical PRRSV strains and propose a first approximation to the criteria to define a virulent PRRSV strain.

Prevalence of mycoplasma-like lung lesions in pigs from commercial farms from Spain and Portugal.

BACKGROUND: Mycoplasma hyopneumoniae causes a chronic respiratory disease that produces important economic losses due to poor productive performance, increased mortality and costs for several control strategies. The prevalence of mycoplasma-like lesions (MLL) at abattoir has been widely studied in different countries, making use of different scoring systems. However, most of them are difficult to apply in abattoirs with high number of pigs sacrificed per hour. For that reason, it is necessary to adapt the scoring system to the reality of the modern abattoir, even if there is a loss of accuracy. Our purpose was to investigate the prevalence and severity of MLL at abattoirs in Spain and Portugal using a 0 to 5 scoring system adapted to abattoirs with high number of sacrificed pigs per hour and to highlight the histopathological diagnosis as confirmatory method to identify patterns of pneumonia correlated to gross lesions. RESULTS: Cranioventral pulmonary consolidation, a typical MLL, was the most frequent lung lesion (30.97 %) detected at the abattoir, followed by dorsocaudal infarcts with pleurisy (12.51 %) and pleurisy alone (6.26 %). The average score for all examined lungs at abattoir was 1.99 out of 5 points. The histopathological study revealed that the 78.17 % of the randomly selected lungs with MLL presented microscopic lesions compatible with M. hyopneumoniae infection. Most bronchointerstitial and interstitial pneumonia lesions had a chronic course while most suppurative and fibrinous bronchopneumonia lesions had an acute course and a higher degree of severity. The combination of microscopic lesions more frequently observed was bronchointerstitial pneumonia + interstitial pneumonia + suppurative bronchopneumonia. CONCLUSIONS: The prevalence of MLL at abattoir was 30.97 %, however, after microscopic examination the real prevalence of lungs with lesions compatible with M. hyopneumoniae infection was reduced up to 24.21 %. The six more prevalent combinations of lesions in the microscopic study involved the 66.13 % of examined lungs, and in all of them, microscopic lesions characteristic of M. hyopneumoniae infection were found, what supports the importance of M. hyopneumoniae as a primary pathogen in cases of PRDC.

Activation of pro- and anti-inflammatory responses in lung tissue injury during the acute phase of PRRSV-1 infection with the virulent strain Lena.

Porcine reproductive and respiratory syndrome virus (PRRSV) plays a key role in porcine respiratory disease complex modulating the host immune response and favouring secondary bacterial infections. Pulmonary alveolar macrophages (PAMs) are the main cells supporting PRRSV replication, with CD163 as the essential receptor for viral infection. Although interstitial pneumonia is by far the representative lung lesion, suppurative bronchopneumonia is described for PRRSV virulent strains. This research explores the role of several immune markers potentially involved in the regulation of the inflammatory response and sensitisation of lung to secondary bacterial infections by PRRSV-1 strains of different virulence. Conventional pigs were intranasally inoculated with the virulent subtype 3 Lena strain or the low virulent subtype 1 3249 strain and euthanised at 1, 3, 6 and 8 dpi. Lena-infected pigs exhibited more severe clinical signs, macroscopic lung score and viraemia associated with an increase of IL-6 and IFN-γ in sera compared to 3249-infected pigs. Extensive areas of lung consolidation corresponding with suppurative bronchopneumonia were observed in Lena-infected pigs. Lung viral load and PRRSV-N-protein+ cells were always higher in Lena-infected animals. PRRSV-N-protein+ cells were linked to a marked drop of CD163+ macrophages. The number of CD14+ and iNOS+ cells gradually increased along PRRSV-1 infection, being more evident in Lena-infected pigs. The frequency of CD200R1+ and FoxP3+ cells peaked late in both PRRSV-1 strains, with a strong correlation between CD200R1+ cells and lung injury in Lena-infected pigs. These results highlight the role of molecules involved in the earlier and higher extent of lung lesions in piglets infected with the virulent Lena strain, pointing out the activation of routes potentially involved in the restraint of the local inflammatory response.

Reassessing the role of internalin B in Listeria monocytogenes virulence using the epidemic strain F2365.

OBJECTIVES: To investigate the contribution to virulence of the surface protein internalin B (InlB) in the Listeria monocytogenes lineage I strain F2365, which caused a deadly listeriosis outbreak in California in 1985. METHODS: The F2365 strain displays a point mutation that hampers expression of InlB. We rescued the expression of InlB in the L. monocytogenes lineage I strain F2365 by introducing a point mutation in the codon 34 (TAA to CAA). We investigated its importance for bacterial virulence using in vitro cell infection systems and a murine intravenous infection model. RESULTS: In HeLa and JEG-3 cells, the F2365 InlB+ strain expressing InlB was ≈9-fold and ≈1.5-fold more invasive than F2365, respectively. In livers and spleens of infected mice at 72 hours after infection, bacterial counts for F2365 InlB+ were significantly higher compared to the F2365 strain (≈1 log more), and histopathologic assessment showed that the F2365 strain displayed a reduced number of necrotic foci compared to the F2365 InlB+ strain (Mann-Whitney test). CONCLUSIONS: InlB plays a critical role during infection of nonpregnant animals by a L. monocytogenes strain from lineage I. A spontaneous mutation in InlB could have prevented more severe human morbidity and mortality during the 1985 California listeriosis outbreak.

Multicenter Stratified Study From Spain About Acceptance of Living Liver Donation Among Veterinarian Students.

Veterinarians often hold decision-making positions in the public health care system, and therefore can influence public opinion about organ donation. The objective is to analyze the attitude of Spanish veterinarian students toward living liver donation (LLD) and to establish which factors have an influence on this attitude. METHODS: A sociological, interdisciplinary, multicenter, and observational study was carried out in the veterinarian students enrolled in Spain (n = 9000) (university academic year 2010-2011). A sample of 2854 students was stratified by geographic area and academic year. A validated questionnaire (PCID-DVH RIOS) was self-administered and completed anonymously. The questionnaire was applied to each academic year at compulsory sessions at randomly selected veterinary schools. Statistical analysis included t test, χ2 test, and logistic regression analysis. RESULTS: Completion rate was 94% (n = 2683); 89% (n = 2345) were in favor of related LLD, and 40% (n = 1053) supported unrelated LLD. The following variables were associated with a more favorable attitude: (1) age (P < .001), (2) sex (P < .001), (3) academic year (P < .001), (4) believing in the possibility of needing a transplant oneself in the future (P < .001), (5) attitude toward deceased donation (P < .001), (6) attitude toward living kidney donation (P < .001), (7) acceptance of a donated liver segment from a family member if one were needed (P < .001), (8) having discussed the subject with one's family (P = .009) and friends (P < .001), (9) a partner's opinion about the subject (P = .002), and (10) fear of the possible mutilation of the body after donation (P < .001). CONCLUSION: Spanish veterinary students have a favorable attitude toward LLD.

Veterinary Students' Attitude Toward Living Kidney Donation: A Multicenter Stratified Study From Spain.

Living kidney related donations (LKRD) should be promoted because of the current deficit of organs for transplantation. The objective of the study was to analyze the attitude of Spanish veterinary students toward LKRD, because they may influence public opinion in the future, and to determine the factors that condition it. METHODS: A sociological, interdisciplinary, multicenter, and observational study was carried out in the veterinary students enrolled in Spain (n = 9000) in the university academic year 2010-2011. A sample of 2815 students was stratified by geographical area and academic year. The students' attitude toward LKRD was assessed using a psychosocial validated questionnaire (PCID-DVR Rios), was self-administered, and was completed anonymously. Veterinary schools were randomly selected. The questionnaire was applied to each academic year at compulsory sessions. Statistical analysis was preformed using t test, χ2 test, and logistic regression analysis. RESULTS: The completion rate was 95% (n = 2683); 93% (n = 2504) were in favor of LKRD and 36% (n = 945) supported unrelated living kidney donation. The following variables were associated with having a more favorable attitude: (1) sex (P < .001), (2) being a student of southern universities (P = .03), (3) attitude toward deceased donation (P < .001), (4) having a father (P < .001) or a mother (P < .001) in favor of organ donation, and (5) having discussed the subject with friends (P = .03) or family (P = .02). However, only 60% would accept a kidney from a relative. CONCLUSION: Spanish veterinary students have a favorable attitude toward LKRD. However, only 60% would accept a kidney from a relative.

Attitude Toward Organ Donation and Transplantation in Veterinary Students: A Multicenter and Stratified Study in Spain.

BACKGROUND: Veterinarians often hold decision-making positions in the public health care system and can therefore influence public opinion about organ donation and transplantation (ODT). The aim of this work was to analyze the attitude of Spanish veterinary students toward ODT, because they may influence public opinion in the future, and to determine the factors that condition it. METHODS: This was a sociologic, interdisciplinary, multicenter, observational study in Spain. The study population was students studying for a veterinary degree in Spain (n = 9000), and a sample of 2815 students (confidence of 99% and precision of ±1%) was stratified by geographic area and academic year. A validated questionnaire of attitude toward ODT (PCID-DTO-Ríos) was self-administered and anonymous. RESULTS: Of the 2815 selected students (2790 plus the 0.9% per type of sample), 2650 completed the questionnaire (response rate, 94.14%): 83% (n = 2207) of the respondents were in favor of donation and 17% against. The following main variables were related to a favorable attitude: being female (odds ratio [OR], 0.752; P = .034); knowing a donor (OR, 1.834; P = .003); having discussed the matter with one's family (OR, 1.587; P = .002); having spoken about the subject in social circles with friends (OR, 1.633; P < .001), and being in favor of donating a deceased family member's organs (OR, 2.403; P < .001). CONCLUSIONS: Seventeen percent of Spanish veterinary students were not in favor of ODT. It is important to know the factors that determine their attitude, because this will make it possible to optimize the resources invested in campaigns to promote ODT and to take more specific action.

Seroprevalence and risk factors of exposure to caprine arthritis-encephalitis virus in southern Spain.

The aim of the present transversal descriptive study was to determine the exposure and risk factors associated with caprine arthritis-encephalitis virus (CAEV) in southern Spain. A total of 3,312 serum samples were collected from goat belonging to three different breeds coming from 48 flocks located in different geographic areas from southern Spain. In addition, health and productive parameters were surveyed during the visit to the herds. Serum samples were analysed by INgezim Maedi Screening (Ingenasa®) ELISA kit. The total percentage of herds exposed to CAEV was 87.71% (CI95 78.42-97.00). A total of 733 goats were seropositive with overall seroprevalence of 23.22% (CI95 21.78-24.65). The intraherd seroprevalence was 20.82%±24.07. Multivariate logistic regression showed significant association between CAEV and the next variables: (i) herd size (P<0.0001; OR: 2.07; CI95: 1.73-2.50), (ii) kidding area (P<0.0020; OR: 1.38; CI95: 1.13-1.69), (iii) cleaning and disinfection program (P<0.0067; OR: 1.90; CI95: 1.43-2.53), (iv) natural mating (P<0.0026; OR: 2.22; CI95: 1.73-2.86) and (v) multiparous (P<0.0001; OR: 2.90; CI95: 2.17-3.87). The results indicate a widespread of CAEV infection in goat herds in southern Spain, being herd size, existence of kidding area, absence of cleaning and disinfection program, natural mating and multiparous goats risk factors for the exposure to CAEV.

Survival of Streptococcus suis, Streptococcus dysgalactiae and Trueperella pyogenes in dry-cured Iberian pork shoulders and loins.

Dry-cured hams, shoulders and loins of Iberian pigs are highly appreciated in national and international markets. Salting, additive addition and dehydration are the main strategies to produce these ready-to-eat products. Although the dry curing process is known to reduce the load of well-known food borne pathogens, studies evaluating the viability of other microorganisms in contaminated pork have not been performed. In this work, the efficacy of the dry curing process to eliminate three swine pathogens associated with pork carcass condemnation, Streptococcus suis, Streptococcus dysgalactiae and Trueperella pyogenes, was evaluated. Results of this study highlight that the dry curing process is a suitable method to obtain safe ready-to-eat products free of these microorganisms. Although salting of dry-cured shoulders had a moderate bactericidal effect, results of this study suggest that drying and ripening were the most important stages to obtain dry-cured products free of these microorganisms.

Attitude toward living kidney donation: differences between students from two Spanish universities.

INTRODUCTION: Due to the current deficit of organs for transplantation, living kidney related donations (LKRD) should be promoted. Veterinarians often hold decision-making positions in the public health care system, and therefore can influence public opinion about organ donation. The objective was to analyze the attitude of Spanish veterinary students toward LKRD because they may influence public opinion in the future, and to determine the factors that condition it. MATERIALS AND METHODS: The study was carried out among fifth-year veterinary science students from 2 southern and southeastern Spanish universities. The students' attitude toward LKRD was assessed using a psychosocial, anonymous, self-administered questionnaire. Statistics used were χ(2) test and Student t test. RESULTS: Data from the southern Spain university included a response rate of 87%. The survey showed that 94% of respondents would donate a kidney to a relative who needed it. This attitude toward LKRD was more favorable in women (P < .001) and in those who had discussed the subject with their families (P = .003). Nevertheless, only 58% would accept a kidney from a family member. Data from the southeastern Spain university included a response rate of 97%: 97% of the respondents would donate a kidney to a relative who needed it. This attitude was not associated with any psychosocial variables. However, only 58% would accept a kidney from a relative. There are no differences between the 2 universities (P = .879). CONCLUSIONS: Although the attitude of veterinary students from southern and southeastern Spain toward LKRD was very favorable and there are no differences between them, only 58% of the students would accept an organ from a relative.

Serosurvey on schmallenberg virus and selected ovine reproductive pathogens in culled ewes from southern Spain.

After the first case of Schmallenberg virus (SBV) was reported in southern Spain (March 2012), a retrospective serological study was carried out in extensive sheep flocks from nearby areas to assess the history of exposure to SBV and other selected ovine reproductive pathogens (Chlamydophila abortus, Coxiella burnetii, Border Disease virus 'BDV', Toxoplasma gondii and Neospora caninum). Secondly, the presence of antibodies was investigated in meat juice samples against selected pathogens to validate their use in serosurveys in sheep. A total of 209 Merina and cross-bred culled ewes belonging to 12 outdoor flocks managed in extensive breeding systems were sampled. Serum and meat juice samples were collected at the slaughterhouse and analysed using commercial ELISA kits. Chlamydophila abortus (62.68%, CI95 56.13-69.23) and Toxoplasma gondii (57.42%, CI95 50.72-64.12) were the most prevalent pathogens. The seroprevalence of BDV (16.27%, CI95 11.27-21.27) and Coxiella burnetii (13.88%, CI95 9.2-18.56) was moderate, and only 4 of 209 animals (1.91%, CI95 1.82-2.96) presented specific antibodies against Neospora caninum or SBV. All the examined ovine flocks were seropositive to three or more pathogens. The highest percentage of seropositive animals was detected for T. gondii-C. abortus coseropositive (25.36%) culled ewes. The concordance between serum and meat juice samples was moderate for T. gondii (κ = 0.419) and BDV (κ = 0.568), and fair for C. abortus (κ = 0.311). Our results show evidence of circulation of SBV from summer 2011 in southern Spain. Furthermore, C. abortus and T. gondii were the most prevalent pathogens associated with sheep in outdoor rearing systems. Finally, these preliminary results point to meat juice samples as a potential biological sample for serosurveys studies on sheep.

Progesterone receptor isoform analysis by quantitative real-time polymerase chain reaction in formalin-fixed, paraffin-embedded canine mammary dysplasias and tumors.

Cloning and sequencing of the progesterone receptor gene in dogs have revealed 2 isoforms, A and B, transcribed from a single gene. Distribution of isoforms A and B in canine mammary lesions has hitherto been investigated only by Western blot analysis. This study analyzed progesterone receptor and its isoforms in formalin-fixed, paraffin-embedded tissue samples from canine mammary lesions (4 dysplasias, 10 benign tumors, and 46 carcinomas) using 1-step SYBR Green quantitative real-time polymerase chain reaction (RT-qPCR). Progesterone receptor was expressed in 75% of dysplasias, all benign tumors, and 59% of carcinomas. Carcinomas, and particularly simple epithelial-type carcinomas, displayed the lowest levels of expression. A high rate of agreement was recorded between RT-qPCR and immunohistochemical labeling. Isoforms A and B were successfully amplified, with correlation coefficients of 0.99 and amplification efficiencies close to 2, and were expressed in all lesion types analyzed. Predominance of A over B expression was observed in carcinomas and complex adenomas. Low-grade tumors exhibited higher progesterone receptor messenger RNA (mRNA) levels, but no difference was observed in the expression of isoform A versus B. Analysis of progesterone receptor mRNA isoforms by RT-qPCR was successful in routinely formalin-fixed, paraffin-embedded tissue samples and enabled the distribution of isoforms A and B to be identified for the first time in dysplasias, benign tumors, and malignant tumors of the canine mammary gland. These findings will facilitate future research into the role of progesterone receptor isoforms in the progression of canine mammary tumors.

Verrucous hemangioma with pseudoepitheliomatous epidermal hyperplasia in an adult horse.

Verrucous hemangiomas are a rare specific variant of equine skin tumors not well described in the literature. An 8-year-old gelding presented a unilateral lesion on the pastern. Macroscopically, the mass showed a warty and verrucous surface with focal ulcerations. The histology showed a dermal proliferation of endothelial-layered capillaries and venules separated by a delicate stroma of scant fibroblasts and collagen deposition, with pseudoepitheliomatous hyperplasia (exuberant reactive irregular epithelial hyperplasia with tongue-like projections extending into the dermis, mimicking downgrowth of squamous cell carcinoma) and orthokeratotic hyperkeratosis of the overlying epidermis. The immunohistochemical study confirmed the endothelial origin of the tumor, and a final diagnosis of verrucous hemangioma with pseudoepitheliomatous hyperplasia was confirmed. To the knowledge of the authors, this is the first detailed description of this entity in adult horses. Moreover, the clinical progression and epidermal changes have not been previously reported, emphasizing the importance of a pathological study of any epithelial preneoplastic lesion to rule out an underlying dermal neoplasia.

A serological survey of Brucella spp., Salmonella spp., Toxoplasma gondii and Trichinella spp. in Iberian fattening pigs reared in free-range systems.

Zoonotic agents such as Brucella spp., Salmonella spp., Toxoplasma gondii and Trichinella spp., all considered high-risk zoonotic pathogens by the European Food Safety Agency (EFSA), may cause no symptoms of infection in free-range pigs yet still have a significant public health impact. A serological survey was therefore performed to determine the history of occurrence of these pathogens in such pigs in southern Spain. A total of 709 serum samples were collected at abattoir from pigs from 79 farms and analysed for specific antibodies against the above pathogens using commercially available ELISA kits. Encysted Trichinella spp. larvae were also sought following the artificial digestion method of diaphragm pillar muscle. The results showed Salmonella spp. to be widely distributed among the sampled herds [73.42%, 95% confidence interval (CI95 ) 65.6-81.78] and Toxoplasma gondii to be present in over half (58.23%, CI95 47.33-69.07). The seroprevalence of Brucella spp. was very low (3.8%, CI95 0.18-7.42), and antibodies against Trichinella spp. were not detected. No encysted Trichinella spp. larvae were microscopically detected.

Downregulation of antigen-presenting cells in tonsil and lymph nodes of porcine reproductive and respiratory syndrome virus-infected pigs.

Porcine reproductive and respiratory syndrome virus (PRRSV) can persist in different organs of infected pigs, which suggests a failure in the immune response. Antigen-presenting cells (APCs) play a pivotal role in the induction of effective T- and B-cell responses. In this study, we investigated the changes in the different APC subpopulations and T- and B-cell counts in the tonsil, retropharyngeal and mediastinal lymph nodes of pigs experimentally infected with a European PRRSV field isolate. Our results demonstrated that the expression of S100, SWC3, HLA-DR molecule and CD3 was diminished in the studied organs throughout the study, observing a significant negative correlation between viral antigen and HLA-DR expression in both retropharyngeal and mediastinal lymph nodes. In contrast, λ-light chains showed an increase during the study. Taking all into account, after PRRSV infection, no enhancement in the number of APCs and T cells was observed, suggesting an impairment of the immune function which may allow the persistence of PRRSV into the organism.

Type 2 Porcine Reproductive and Respiratory Syndrome Virus infection mediated apoptosis in B- and T-cell areas in lymphoid organs of experimentally infected pigs.

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection is characterized by persisting in lungs and lymphoid tissue, resulting in systemic lymphoid depletion. The aim of this study was to correlate the histological changes, viral antigen expression and apoptosis phenomena in tonsil, medial retropharyngeal and mediastinal lymph nodes of 12 pigs inoculated with a type 2 PRRSV isolate (Chilean strain 2402). Apoptosis phenomena were observed mainly in lymphocytes and secondly in macrophages of lymph nodes and tonsils of inoculated animals, showing a peak of both apoptotic cells and viral antigen expression at the end of the study (21 dpi). However, the number of apoptotic cells was higher than the number of PRRSV-positive cells at the end of the study. This finding together with the location of apoptotic cells and PRRSV-positive cells in different structures of lymphoid organs supports the hypothesis that PRRSV-positive macrophages might modulate the apoptosis phenomena in other cells, mainly lymphocytes, by means of an indirect mechanism. Furthermore, apoptotic cells were detected both in B- and T-cell areas of lymphoid organs, suggesting that apoptosis phenomena may play a role in the impairment of the host immune response during PRRS.