Lesions In Piglets Research Articles

Transcriptomic Analysis of PDCoV-Infected HIEC-6 Cells and Enrichment Pathways PI3K-Akt and P38 MAPK.

Porcine Deltacoronavirus (PDCoV) is a newly identified coronavirus that causes severe intestinal lesions in piglets. However, the understanding of how PDCoV interacts with human hosts is limited. In this study, we aimed to investigate the interactions between PDCoV and human intestinal cells (HIEC-6) by analyzing the transcriptome at different time points post-infection (12 h, 24 h, 48 h). Differential gene analysis revealed a total of 3560, 5193, and 4147 differentially expressed genes (DEGs) at 12 h, 24 h, and 48 h, respectively. The common genes among the DEGs at all three time points were enriched in biological processes related to cytokine production, extracellular matrix, and cytokine activity. KEGG pathway analysis showed enrichment of genes involved in the p53 signaling pathway, PI3K-Akt signaling pathway, and TNF signaling pathway. Further analysis of highly expressed genes among the DEGs identified significant changes in the expression levels of BUB1, DDIT4, ATF3, GBP2, and IRF1. Comparison of transcriptome data at 24 h with other time points revealed 298 DEGs out of a total of 6276 genes. KEGG analysis of these DEGs showed significant enrichment of pathways related to viral infection, specifically the PI3K-Akt and P38 MAPK pathways. Furthermore, the genes EFNA1 and KITLG, which are associated with viral infection, were found in both enriched pathways, suggesting their potential as therapeutic or preventive targets for PDCoV infection. The enhancement of PDCoV infection in HIEC-6 was observed upon inhibition of the PI3K-Akt and P38 MAPK signaling pathways using sophoridine. Overall, these findings contribute to our understanding of the molecular mechanisms underlying PDCoV infection in HIEC-6 cells and provide insights for developing preventive and therapeutic strategies against PDCoV infection.

Isolation and pathogenicity comparison of two novel natural recombinant porcine reproductive and respiratory syndrome viruses with different recombination patterns in Southwest China.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses in the swine industry. Frequent mutations and recombinations account for PRRSV immune evasion and the emergence of novel strains. In this study, we isolated and characterized two novel PRRSV-2 strains from Southwest China exhibiting distinct recombination patterns. They were designated SCABTC-202305 and SCABTC-202309. Phylogenetic results indicated that SCABTC-202305 was classified as lineage 8, and SCABTC-202309 was classified as lineage 1.8. Amino acid mutation analysis identified unique amino acid substitutions and deletions in ORF5 and Nsp2 genes. The results of the recombination analysis revealed that SCABTC-202305 is a recombinant with JXA1 as the major parental strain and NADC30 as the minor parental strain. At the same time, SCABTC-202309 is identified as a recombinant with NADC30 as the major parental strain and JXA1 as the minor parental strain. In this study, we infected piglets with SCABTC-202305, SCABTC-202309, or mock inoculum (control) to study the pathogenicity of these isolates. Although both isolated strains were pathogenic, SCABTC-202305-infected piglets exhibited more severe clinical signs and higher mortality, viral load, and antibody response than SCABTC-202309-infected piglets. SCABTC-202305 also caused more extensive lung lesions based on histopathology. Our findings suggest that the divergent pathogenicity observed between the two novel PRRSV isolates may be attributed to variations in the genetic information encoded by specific genomic regions. Elucidating the genetic determinants governing PRRSV virulence and transmissibility will inform efforts to control this devastating swine pathogen.IMPORTANCEPorcine reproductive and respiratory syndrome virus (PRRSV) is one of the most critical pathogens impacting the global swine industry. Frequent mutations and recombinations have made the control of PRRSV increasingly difficult. Following the NADC30-like PRRSV pandemic, recombination events involving PRRSV strains have further increased. We isolated two novel field PRRSV recombinant strains, SCABTC-202305 and SCABTC-202309, exhibiting different recombination patterns and compared their pathogenicity in animal experiments. The isolates caused higher viral loads, persistent fever, marked weight loss, moderate respiratory clinical signs, and severe histopathologic lung lesions in piglets. Elucidating correlations between recombinant regions and pathogenicity in these isolates can inform epidemiologic tracking of emerging strains and investigations into viral adaptive mechanisms underlying PRRSV immunity evasion. Our findings underscore the importance of continued genomic surveillance to curb this economically damaging pathogen.

Experimental Inoculation of Porcine Circovirus 3 (PCV-3) in Pregnant Gilts Causes PCV-3-Associated Lesions in Newborn Piglets that Persist until Weaning

Porcine circovirus 3 (PCV-3) has been detected in cases of reproductive failure but the pathogenesis of such infection is poorly understood. So far, experimental PCV-3 inoculations have been performed only in piglets. Therefore, through the experimental inoculation of pregnant gilts at two different time points (second and last third of gestation), this study aimed to evaluate the outcome of PCV-3 infection in dams and their offspring until weaning age. Two weeks postinoculation, all gilts became viremic and the infection lasted until the end of study. Farrowing occurred naturally, without evidence of reproductive disorders, and piglets showed no significant clinical signs from farrowing to weaning (21 day-old). However, majority of the delivered piglets were viremic, mostly until weaning age. Both newborn and weaned pigs showed different degrees of systemic, lymphohistiocytic arteritis and periarteritis. Lesions were more severe in the piglets infected during the second third of gestation and worsened at weaning. Additionally, PCV-3 detection in nervous and cardiac tissue and development of histopathological lesions in these tissues were gestational dependent, as only occurred in piglets infected at second third of pregnancy. Piglets with lesions raised to weaning age had less body weight than those without them. This study represents the first description of a PCV-3 experimental infection in pregnant gilts, which resulted in transplacental infection, histological lesions in piglets mimicking those of natural occurring disease, and lesser body weight in piglets with vascular lesions at weaning age. Obtained results allowed proposing a potential pathogenesis model for PCV-3 infection in swine.

Isolation, identification, and pathogenicity of porcine epidemic diarrhea virus.

Porcine epidemic diarrhea (PED) is an enterophilic infectious disease caused by the porcine epidemic diarrhea virus (PEDV), which can lead to dehydration-like diarrhea in piglets with a mortality rate of up to 100%, causing huge economic losses to the global pig industry. In this study, we isolated two PEDV strains, FS202201 and JY202201, from diarrheal samples collected from two new PED outbreak farms in 2022. We performed phylogenetic analysis of the S gene and whole gene sequence. The effects of the different mutations on viral pathogenicity were investigated using piglet challenge experiments. The results showed that both strains belong to the G2c subtype, a widely prevalent virulent strain. Compared with FS202201, JY202201 harbored substitution and deletion mutations in nsp1. Both FS202201 and JY202201 infected piglets showed severe diarrhea and significant intestinal tissue lesions at an infection dose of 104 TCID50/mL, with a mortality rate of 50%; however, JY202201 required an additional day to reach mortality stabilization. An infection dose of 103 TCID50/mL reduced diarrhea and intestinal tissue lesions in piglets, with mortality rates of the two strains at 16.7% and 0%, respectively. In addition, PEDV was detected in the heart, liver, spleen, lungs, kidneys, mesenteric lymph nodes, stomach, large intestine, duodenum, jejunum, and ileum, with the highest levels in the intestinal tissues. In conclusion, this study enriches the epidemiology of PEDV and provides a theoretical basis for the study of its pathogenic mechanism and prevention through virus isolation, identification, and pathogenicity research on newly identified PED in the main transmission hub area of PEDV in China (Guangdong).

Histopathological Pulmonary Lesions in 1st-Day Newborn Piglets Derived from PRRSV-1 MLV Vaccinated Sows at the Last Stage of Gestation.

Modified live virus (MLV) vaccines for the control of porcine respiratory and reproductive syndrome virus (PRRSV) have been associated with the vertical and horizontal transmission of vaccine viruses. The present study aimed to describe pathological lung lesions in piglets born by gilts vaccinated with PRRSV-1 MLV. In total, 25 gilts were vaccinated at late gestation (100th day) and were divided into five groups according to the different vaccines (Vac) used: no vaccine-control group, Vac-1-strain DV, Vac-2-strain VP-046 BIS, Vac-3-strain 94881, Vac-4-strain 96V198. Within the first 0-9 h of the farrowing, blood samples were collected from all newborn piglets and lung samples were exanimated grossly, histopathologically and with scanning electron microscopy. PRRSV (RT-PCR-positive) and antibodies were detected in the serum of piglets from gilts vaccinated with Vac-2. In these piglets, moderate to severe interstitial pneumonia with thickened alveolar septa was noticed. Type II pneumocyte hyperplasia was also observed. The rest of the trial piglets showed unremarkable lung lesions. Phylogenetic analysis revealed the 98.7% similarity of the PRRSV field strain (GR 2019-1) to the PRRS MLV vaccine strain VP-046 BIS. In conclusion, the Vac-2 PRRSV vaccine strain can act as an infectious strain when vaccination is administrated at late gestation, causing lung lesions.

Streptococcus suis contributes to inguinal lymph node lesions in piglets after highly pathogenic porcine reproductive and respiratory syndrome virus infection.

The swine pathogens porcine reproductive and respiratory syndrome virus (PRRSV) and Streptococcus suis have both been reported to cause damage to the immune organs. Inguinal lymph node (ILN) injury has been reported in PRRSV-infected pigs with secondary S. suis infection, but not much is known about the mechanism. In this study, secondary S. suis infection after highly pathogenic (HP)-PRRSV infection caused more severe clinical symptoms, mortality, and ILN lesions. Histopathological lesions were seen in ILNs with a marked decrease in lymphocyte numbers. Terminal deoxynucleotidyl transferase (TdT)-mediated de-oxyuridine triphosphate (dUTP)-biotin nick end-labeling (TUNEL) assays revealed that HP-PRRSV strain HuN4 alone induced ILN apoptosis, but dual-infection with S. suis strain BM0806 induced greater levels of apoptosis. Besides, we found that some HP-PRRSV-infected cells underwent apoptosis. Furthermore, anti-caspase-3 antibody staining confirmed that ILN apoptosis was mainly induced by a caspase-dependent pathway. Pyroptosis was also observed in HP-PRRSV-infected cells, and there was more pyroptosis in piglets infected with HP-PRRSV alone compared with those with secondary S. suis infection, and HP-PRRSV-infected cells underwent pyroptosis. Altogether, this is the first report to identify pyroptosis in ILNs and which signaling pathway is related to ILN apoptosis in single or dual-infected piglets. These results contribute to a better understanding of the pathogenic mechanisms during secondary S. suis infection.

Identifying areas of animal welfare concern in different production stages in Danish pig herds using the Danish Animal Welfare Index (DAWIN).

Animal welfare is of increasing public interest, and the pig industry in particular is subject to much attention. The aim of this study was to identify and compare areas of animal welfare concern for commercial pigs in four different production stages: (1) gestating sows and gilts; (2) lactating sows; (3) piglets; and (4) weaner-to-finisher pigs. One welfare assessment protocol was developed for each stage, comprising of between 20 and 29 animal welfare measures including resource-, management- and animal-based ones. Twenty-one Danish farms were visited once between January 2015 and February 2016 in a cross-sectional design. Experts (n = 26; advisors, scientists and animal welfare controllers) assessed the severity of the outcome measures. This was combined with the on-farm prevalence of each measure and the outcome was used to calculate areas of concern, defined as measures where the median of all farms fell below the value defined as 'acceptable welfare.' Between five and seven areas of concern were identified for each production stage. With the exception of carpal lesions in piglets, all areas of concern were resource- and management-based and mainly related to housing, with inadequate available space and the floor type in the resting area being overall concerns across all production stages. This means that animal-based measures were largely unaffected by perceived deficits in resource-based measures. Great variation existed for the majority of measures identified as areas of concern, demonstrating that achieving a high welfare score is possible in the Danish system.

Full genome characterization of a human-porcine reassortment G12P[7] rotavirus and its pathogenicity in piglets.

In recent years, increasing numbers of cases of acute gastroenteritis caused by Group A rotavirus (RVA) G12 strains have been reported in humans from many countries around the world, but G12 RVA detection in animals is currently less reported. Pigs are an important animal reservoir of zoonotic RVs and a mixing vessel for RVs. In 2020, RVA infection cases in piglets increased in China, which attracted more attention. During an epidemiological survey, a new type of porcine G12P[7] strain (CN127) was detected in pig farms across several provinces. Complete genome analyses revealed that strain CN127 possessed a Wa-like backbone with a genotype constellation of G12-P[7]-I1-C1-M1-R1-A8-N1-T1-E1-H1. The A8 genotype is indicative of its porcine rotavirus origin. Sequence identities and phylogenetic analyses showed that the VP2, VP4, NSP1, NSP4 and NSP5 genes were most closely related to those of porcine rotaviruses, but the VP1, VP6, VP7 and NSP2-3 genes were most closely related to those of human rotaviruses. CN127 likely emerged due to genetic reassortment between porcine and human rotavirus. In vivo experiments showed that CN127 infection caused gastrointestinal tract lesions in piglets and histopathological changes in the lung, liver and mesenteric lymph nodes (MLNs). In the small intestine, RVA antigen was detected in the duodenum and jejunum but not in the ileum. In the extra-intestinal tissues, RVA antigen was detected in the lung but not in the MLNs. Viral RNA was detected in the intestinal and extra-intestinal tissues as well as blood. This study reveals that RVA G12P[7] may become an epidemicstrain in China and also provides further evidence that cocirculating human and porcine strains could produce new genotype rotaviruses with high virulence in piglets.

M6A RNA Methylation Mediates NOD1/NF-kB Signaling Activation in the Liver of Piglets Challenged with Lipopolysaccharide.

N6-methyladenosine (m6A) is the most abundant internal modification that widely participates in various immune and inflammatory responses; however, its regulatory mechanisms in the inflammation of liver induced by lipopolysaccharide in piglets remain largely unknown. In the present study, piglets were intraperitoneally injected with 80 μg/kg LPS or an equal dose of sterile saline. Results indicated that LPS administration increased activities of serum alanine aminotransferase (ALT), induced M1 macrophage polarization and promoted secretion of inflammatory cytokines, and finally led to hepatic lesions in piglets. The NOD1/NF-κB signaling pathway was activated in the livers of the LPS group. Moreover, the total m6A level was significantly elevated after LPS treatment. MeRIP-seq showed that 1166 and 1344 transcripts contained m6A methylation in control and LPS groups, respectively. The m6A methylation sites of these transcripts mainly distributes in the 5′ untranslated region (5′UTR), the coding sequence (CDS), and the 3′ untranslated region (3′UTR). Interestingly, these genes were mostly enriched in the NF-κB signaling pathway, and LPS treatment significantly changed the m6A modification in NOD1, RIPK2, NFKBIA, NFKBIB, and TNFAIP3 mRNAs. In addition, knockdown of METTL3 or overexpression of FTO both changed gene levels in the NOD1/NF-κB pathway, suggesting that activation of this pathway was regulated by m6A RNA methylation. Moreover, the alteration of m6A RNA methylation profile may be associated with the increase of reactive oxygen species (ROS), HIF-1α, and MAT2A. In conclusion, LPS activated the NOD1/NF-κB pathway at post-transcriptional regulation through changing m6A RNA methylation, and then promoted the overproduction of proinflammatory cytokines, ultimately resulting in liver inflammation and damage.

53 Risk factors for facial lesions in piglets and teat injuries in sows – a review

Abstract Painful procedures performed on piglets are one of the most important welfare concerns of intensive pig production. For example, teeth resection is a common practice whereby the canine (needle) teeth are clipped or ground to prevent piglet facial and sow teat lesions. Based on a global consumer survey in 2018, 60% of respondents will potentially stop purchasing pork from pigs experiencing painful procedures. In contrast to tail docking and surgical castration, little is known about the risk factors for piglet facial and sow teat lesions and therefore the need for teeth resection. We reviewed the literature to better understand these risk factors and conducted a survey to identify preventative strategies in practice that have enabled producers to avoid teeth resection. For the literature review, we used Web of Science and Google Scholar to include peer-reviewed publications and gray literature. The questionnaire was distributed with convenience sampling to relevant stakeholders. In the questionnaire, information on current on-farm practices regarding teeth resection was collected, including the method, frequency, and reason for conducting teeth resection, and preventative measures used. Preliminary findings of the literature review showed that most studies only focused on teeth resection and its effect on piglet facial and sow teat lesions. Other risk factors identified are litter size, farrowing system and flooring, milk production, management of fostering, flooring, and enrichment. The survey is ongoing and the complete results will be presented during the conference. Our review suggests many risk factors are related to piglet facial and sow teat lesions other than whether or not teeth resection is carried out. There is still a knowledge gap in the understanding of how alleviating these risk factors can prevent said lesions, and further research and dissemination of best practice is needed to explore different solutions instead of solely relying on teeth resection.

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.

Early infection of Streptococcus suis serotype 2 increases the virulence of highly pathogenic porcine reproductive and respiratory syndrome MLV-like virus in pigs

Modified-live virus (MLV) vaccines derived from highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) were wildly used in China, which resulted in the emergence of MLV-like strains in pigs. Previous studies demonstrated that secondary bacterial infection could enhance HP-PRRSV infection-mediated inflammatory responses, but it is unknown whether early bacterial infection could enhance the HP-PRRSV MLV-like infection-mediated pathological reaction. In this paper, to gain the evidence for infection of pigs with MLV-like strains in China, we firstly analyzed the genetic characterization of the HP-PRRSV MLV-like isolate (TJxq1701) and further evaluated whether the early Streptococcus suis infection synergizes HP-PRRSV MLV-like infection-mediated pathological reaction. Our results showed that the whole genome of TJxq1701 shared the highest homology with JXA1-P80 and a total of 16 amino acids residues unique to JXA1-P80 in ORF1a, ORF1b, GP2, GP3, GP4, and GP5 were found in the corresponding locations. The results of infection experiments in pigs revealed that TJxq1701 caused transitional fever, moderate respiratory clinical sign and microscopic lung lesions in piglets, but early infection with low virulence Streptococcus suis serotype 2 (SS2) exhibited seriously clinical signs, including high fever, anorexia, and respiratory distress, leading to 60% mortality within four weeks in comparison with alone infected group. Taken together, our findings reveal that early bacterial infection could enhance the HP-PRRSV MLV-like infection-mediated pathological reaction, which provide an important clue for understanding that streptococcus infection increases the pathogenicity of MLV-like virus and a new thought for prevention and control of PRRSV.

Susceptibility of porcine pulmonary microvascular endothelial cells to porcine reproductive and respiratory syndrome virus.

Microvascular endothelial cells possess versatile functions and their roles in a variety of viral infections have been documented. Porcine reproductive and respiratory syndrome virus (PRRSV) infection induces severe lung inflammatory lesions in piglets, which is manifested as pulmonary endothelial dysfunction. However, the underlying mechanism of PRRSV affecting porcine pulmonary microvascular endothelial cells (PMECs) remains unknown. This study aimed to evaluate the susceptibility of PMECs to PRRSV. Primary PMECs were isolated and purified from piglet lungs, and the expression of three PRRSV receptors was characterized using immunofluorescence. Overt cytopathic effects of the PRRSV strain HN in PMECs were observed at day five post-infection, and PRRSV antigens in PMECs were determined at both RNA and protein levels using immunofluorescence and quantitative RT-PCR assays. The viral antigen significantly increased at 96 hr post-infection, and infectious virus was recovered from the supernatant of the infected PMECs. The results show that PMECs can be infected with the PRRSV strain HN, and that their receptor expression pattern is different from that of alveolar macrophages. The results of this study shed light on the potential roles of PMECs in PRRSV infection and provide a comprehensive understanding of the pathogenesis underlying its severe manifestation.

ITRAQ-based quantitative proteomics reveals the first proteome profiles of piglets infected with porcine circovirus type 3

Porcine circovirus type 3 (PCV3) infection induces porcine dermatitis and nephropathy syndrome, reproductive failure, and multisystemic inflammatory lesions in piglets and sows. To better understand the host responses to PCV3 infection, isobaric tags for relative and absolute quantification (iTRAQ) labeling combined with LC-MS/MS analysis was used for quantitative determination of differentially regulated cellular proteins in the lungs of specific-pathogen-free piglets after 4 weeks of PCV3 infection. Totally, 3429 proteins were detected in three independent mass spectrometry analyses, of which 242 differential cellular proteins were significantly regulated, consisting of 100 upregulated proteins and 142 downregulated proteins in PCV3-infected group relative to control group. Bioinformatics analysis revealed that these higher or lower abundant proteins involved primarily metabolic processes, innate immune response, MHC-I and MHC-II components, and phagosome pathways. Ten genes encoding differentially regulated proteins were selected for investigation via real-time RT-PCR. The expression levels of six representative proteins, OAS1, Mx1, ISG15, IFIT3, SOD2, and HSP60, were further confirmed by Western blotting and immunohistochemistry. This study attempted for the first time to investigate the protein profile of PCV3-infected piglets using iTRAQ technology; our findings provide valuable information to better understand the mechanisms underlying the host responses to PCV3 infection in piglets. SignificanceOur study identified differentially abundant proteins related to a variety of potential signaling pathways in the lungs of PCV3-infected piglets. These findings provide valuable information to better understand the mechanisms of host responses to PCV3 infection.

Attenuation and characterization of porcine enteric alphacoronavirus strain GDS04 via serial cell passage

Porcine enteric alphacoronavirus (PEAV) is a newly identified swine enteropathogenic coronavirus that causes watery diarrhea in newborn piglets. In this study, an original, highly virulent PEAV strain GDS04 was serially passaged in Vero cells. The virus titers and sizes of syncytia increased gradually with the cell passages. Newborn piglets were orally inoculated with PEAV P15, P67 and P100. Compared with P15 and P67, P100 resulted in only mild clinical signs and intestinal lesions in piglets. The virus shedding in feces and viral antigens in intestinal tract were markedly reduced in P100-inoculated piglets. Importantly, all P100-inoculated newborn piglets survived, indicating that P100 was an attenuated variant. Sequence analysis revealed that the virulent strain GDS04 had four, one, six and eleven amino acid differences in membrane, nucleocapsid, spike and ORF1ab proteins, respectively, from P100. Furthermore, more differences in the predicted three-dimensional structure of S protein between GDS04 and P100 were observed, indicating that these differences might be associated with the pathogenicity of PEAV. Collectively, our research successfully prepared a PEAV attenuated variant which might serve as a live attenuated vaccine candidate against PEAV infection.

Los procedimientos dentales postnatales afectan la ganancia de peso y el bienestar de los lechones

Objetivo. Este estudio fue realizado para evaluar la ganancia de peso, mortalidad, proteínas plasmáticas (BP), lesiones faciales en los lechones y en las cerdas, grasa dorsal (P2) y lesiones en los pezones en lechigadas sometidas a diferentes manejos dentales. Materiales y métodos. La investigación fue conducida en una granja comercial de cría. Fueron utilizadas quince cerdas, divididas en tres grupos: control, en el cual los dientes de los lechones permanecieron intactos; descolmille con alicate; descolmille con limadora eléctrica. Nosotros evaluamos WG, BP (cinco machos/lechigada), mortalidad, lechones de baja viabilidad y lesiones faciales en los lechones. En las cerdas, nosotros evaluamos P2 y la escala de lesiones en los pezones. Los datos de BP, escala de lesiones y WG fueron evaluados individualmente. Para el WG, el peso inicial y el tamaño de la lechigada fueron considerados. Acerca de las otras variables, nosotros usamos el peso promedio de la lechigada. Cuando hubo diferencias, las medias fueron comparadas usando la prueba de Duncan (p<0.05). Resultados. En la primera semana, los lechones del GT presentaron mayor WG. En la segunda semana el CT presentó la peor WG. En las dos primeras semanas así como en el período total, los lechones del CT presentaron peor WG de que los del GT. La mortalidad y los lechones de baja viabilidad no fueron influenciados. Después del cuarto día, el CT y el GT redujeron las lesiones faciales. No hubo efectos en BP. Los tratamientos no influenciaron P2 y las lesiones en los pezones. Conclusiones. Los tratamientos no influenciaron en la mortalidad, lechones de baja viabilidad, BP de los lechones y en la escala de lesiones en los pezones de las cerdas. CT redujo la ganancia y IT aumentó las lesiones faciales.

A recombinant type 2 porcine reproductive and respiratory syndrome virus between NADC30-like and a MLV-like: Genetic characterization and pathogenicity for piglets

Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically important pathogen for swine industry worldwide. The recombination occurring among PRRSV strains has been recognized as one of important molecular mechanisms for the evolution of PRRSV. Current prevalence of PRRSV NADC30-like causing clinical disease outbreaks is highly concerned in China. In the present study, the genetic characterization of a recombinant type 2 PRRSV (designated TJnh1501) was analyzed and its pathogenicity for piglets was examined. Our study showed that each region of TJnh1501 genome had 96.67–100% nucleotide and 96.5–100% amino acid identities with a Chinese highly pathogenic PRRSV-derived modified-live virus (MLV)-like except for its nonstructural protein 2 (nsp2)-coding region; while its nsp2-coding region shared higher nucleotide (84.44–85.85%) and amino acid (82.44–84.79%) identities with NADC30 and NADC30-like CHsx1401, and in particular, the highly variable region of nsp2 exhibited characteristic 131-aa deletion identical to NADC30 and NADC30-like CHsx1401. Meanwhile, we identified two recombination breakpoints located in the nt1737 and nt3506 of nsp2-coding region, which had higher nucleotide homology with NADC30 and NADC30-like CHsx1401. Moreover, TJnh1501 infection could cause persistent fever, moderate respiratory clinical signs, higher viremia, and obvious gross and microscopic lung lesions in piglets. The virus was shown to have lower pathogenicity than HP-PRRSV JXwn06, but higher than NADC30-like CHsx1401 for piglets. Our findings reveal that TJnh1501 is a recombinant type 2 PRRSV from the recombinant event between NADC30-like and MLV-like derived from the Chinese highly pathogenic PRRSV, and it exhibits intermediate virulence for pigs. This study adds valuable evidence for understanding the role of genomic recombination in the evolution of PRRSV.

Genomic characterization and pathogenicity of a strain of type 1 porcine reproductive and respiratory syndrome virus

The emergence of type 1 porcine reproductive and respiratory syndrome virus (PRRSV) has been noticed recently in China. In the present study, the complete genomic characterization of a strain of type 1 PRRSV (designated GZ11-G1) was described and its pathogenicity for piglets was analyzed. The results showed that the complete genome of GZ11-G1 with a size of 15,094 nt, excluding the poly (A) tails, shared 80.2–96.3% identity with the representative strains of type 1 PRRSV, and in particular, it had highest homology (96.3%) with Amervac PRRS, a live vaccine virus of type 1 PRRSV and SHE, a rescued virus from an infectious clone of Amervac PRRS virus. Compared with the vaccine virus, the nonstructural and structural proteins of GZ11-G1 displayed extensive amino acid variations except for its ORF5a. GZ11-G1 was clustered with the strains of type 1 PRRSV including Cresa3267, Cresa3249, Cresa3256, Olot/91, 9625/2012, ESP-1991-Olot91 and Amervac PRRS vaccine virus by further phylogenetic analysis. Moreover, GZ11-G1 was shown to cause fever, higher viremia and lung and lymph node lesions in piglets. Our findings indicate that GZ11-G1 is genetically related to type 1 PRRSV strains within the cluster formed by Cresa3267, Cresa3249, Cresa3256, Olot/91, 9625/2012, ESP-1991-Olot91 and Amervac PRRS vaccine virus, and it is a pathogenic for piglets. This study aids in understanding the genetic variation and evolution of type 1 PRRSV.

Characterizing the thymic lesions in piglets infected with attenuated strains of highly pathogenic porcine reproductive and respiratory syndrome virus

Piglets infected with the highly pathogenic PRRSV (HP-PRRSV) HuN4 strain develop severe thymus atrophy. However, the attenuated strain HuN4-F112 does not lead to lesions in organs. Here, we have characterized the thymic lesions in piglets infected with attenuated strains of HP-PRRSV HuN4 isolated at different passages in the attenuation process to produce HuN4-F112 from the parent HuN4 strain (HuN4-F5, HuN4-F15, HuN4-F23, HuN4-F30, and HuN4-F112). The thymic effects of infection were evaluated in terms of the thymus/body weight ratio, pathological changes, and thymocytes apoptosis. The ability of HP-PRRSV to induce thymus atrophy was reduced following attenuation after 23 passages; the HuN4-F23, but not HuN4-F30, caused thymus atrophy. The ability of the virus to induce thymocyte apoptosis decreased as it became attenuated. In addition, the viral load in the thymus was reduced as the virus was attenuated. The HuN4-F23 and HuN4-F30 strains might provide insight into the molecular mechanisms of HP-PRRSV pathogenesis. Taken together, our results indicate that the ability of HP-PRRSV to induce thymic atrophy is related to its pathogenicity.

A cross-sectional study on the prevalence and risk factors for foot and limb lesions in piglets on commercial farms in Ireland

A cross-sectional survey of 68 integrated Irish pig farms was conducted to determine the prevalence and risk factors for foot and limb lesions in 2948 piglets from 272 litters. One litter was selected per age category; 3–7 days, 8–14 days, 15–21 days and 22–28 days per farm. All piglets were examined for sole bruising, sole erosion, coronary band injuries, limb abrasions, alopecia, swollen limbs and swollen feet and scored from 0 to 3 based on relative size. Environmental parameters were recorded for each litter examined. A questionnaire was completed on management, health and performance factors for each farm. The overall prevalence of each lesion was calculated and multilevel mixed effect logistic regression models were used to elucidate risk factors. The prevalence (farm range) of lesions were: sole bruising=61.5% (7–100%), sole erosion=34.1% (0–100%), coronary band injuries=11.3% (0–46%), limb abrasions=55.7% (11–98%), alopecia=24.8% (0–83%), swollen limbs=2.4% (0–11%) and swollen feet=4.4% (0–14%). Age was negatively associated with sole bruising (OR 0.42; CI 0.37, 0.50) and coronary band injury (OR 0.69; CI 0.60, 0.81) and positively associated with limb abrasions (OR 1.54; CI 1.12, 2.14). There was a reduced risk of sole bruising in piglets in pens with plastic slats with oval voids in the piglet area of the pen with a plastic solid area for piglets and metal slats under the crate (OR 0.32; CI 0.15, 0.70) compared with plastic stats throughout and a plastic solid area for piglets. There was an increased risk of sole erosion (OR 1.81; CI 1.07, 3.09) and foot and limb swellings (OR 1.90; CI 1.01, 3.57) in pigs in pens with metal slats only and a solid plastic area for piglets compared with plastic stats throughout and a solid plastic area for piglets. There was an increased risk of coronary band injury in pens with metal slats throughout and a metal solid area for piglets (OR 4.25; CI 1.96, 3.57) compared with plastic stats throughout and a plastic solid area for piglets. We conclude no single floor type was ideal for piglet foot and limb health with all floors influencing different lesions in different ways, however, the positive association between sole erosions, coronary band injury and foot and limb swellings and metal slats suggest that this floor type was most detrimental and most likely to be associated with joint infections that lead to severe health and welfare concerns.