Pathological evaluation of reproductive system of porcine reproductive and respiratory syndrome virus-vaccinated and nonvaccinated anestrus sows and gilts

Glycosylated protein 4-deficient PRRSV in complementing cell line shows low virus titer

Porcine Reproductive and Respiratory Syndrome (PRRS) threats the swine industry seriously. The spread of live vaccine virus leads to the emergence of recombinant virus, which brings biosafety problems. The replication-deficient virus as a vaccine candidate would avoid this problem. In the present study, the recombinant lentiviral plasmid pLV-EF1α-EGFP-2A-ORF4 was co-transfected with lentivirus in HEK293FT cells. The transfection mixture was harvested and transduced into Marc-145 to screen a cell line stably expressing the PRRSV ORF4 with puromycin. The cell line Marc-145-GP4 was confirmed with PCR, RT-PCR, IFA, and Western blotting using a monoclonal antibody against Glycoprotein 4 (GP4) of PRRSV. To obtain a replication-deficient PRRSV, Western blotting the recombinant plasmid pNM09-ΔORF4 was constructed by Overlap PCR and DNA recombinant technology with the pNM09 as a backbone plasmid. The pNM09-ΔORF4 was transfected into Marc-145-GP4 with electroporation after transcription in vitro. The replication-deficient virus was rescued on Marc-145-GP4 cells with trans-complementation of ORF4 gene and verified by RT-PCR and IFA. The results indicated that a cell line Marc-145-GP4 stably expressed PRRSV ORF4 was obtained. The recombinant GP4 was successfully expressed and obtained a monoclonal antibody Anti-A-GP4-70, which can specifically react with the virus. Finally, the replication-deficient virus rNM09-ΔORF4 can be rescued with low titer and could only reproduce on the Marc-145-GP4 cells. Unfortunately, the rNM09-ΔORF4 showed too low virus replication titer to determine it. This study lays the foundation for the rapid detection of PRRS and the functional study of GP4 and provides experience for replication-deficient PRRSV.

Damage to intestinal barrier integrity in piglets caused by porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome (PRRS) induces respiratory disease and reproductive failure accompanied by gastroenteritis-like symptoms. The mechanism of intestinal barrier injury caused by PRRSV infection in piglets has yet to be investigated. An in vivo PRRSV-induced model was established in 30-day-old piglets by the intramuscular injection of 2 mL of 10⁴ TCID₅₀/mL PRRSV for 15 days. Observations of PRRSV replication and histology were conducted in the lungs and intestine, and goblet cell counts, relative MUC2 mRNA expression, and tight junction protein, proinflammatory cytokine, TLR4, MyD88, IκB and p-IκB expression were measured. PRRSV replicated in the lungs and small intestine, as demonstrated by absolute RT-qPCR quantification, and the PRRSV N protein was detected in the lung interstitium and jejunal mucosa. PRRSV infection induced both lung and gut injury, markedly decreased villus height and the villus to crypt ratio in the small intestine, and obviously increased the number of goblet cells and the relative expression of MUC2 mRNA in the jejunum. PRRSV infection aggravated the morphological depletion of tight junction proteins and increased IL-1β, IL-6, IL-8 and TNF-α expression by activating the NF-κB signalling pathway in the jejunum. PRRSV infection impaired intestinal integrity by damaging physical and immune barriers in the intestine by inducing inflammation, which may be related to the regulation of the gut-lung axis. This study also provides a new hypothesis regarding the pathogenesis of PRRSV-induced diarrhoea.

Histopathological changes of reproductive organs of goats immunized with Corynebacterium pseudotuberculosis killed vaccine

Caseous lymphadenitis (CLA) caused by Corynebacterium pseudotuberculosis is characterized by the development of abscesses, mainly in superficial and internal lymph nodes, visceral and reproductive organs in small ruminants. This study aims to examine the histopathological changes in reproductive organs of goats immunized with killed vaccine of C. pseudotuberculosis. In this study, twenty four (24) clinically healthy bucks and does were divided into four groups A, B, C and D. Animals in groups A and B were immunized with 0.5 and 1% formalin killed vaccine, respectively; followed by a booster dose. After the booster dose of immunization, groups A, B and C were challenged with C. pseudotuberculosis at 10⁶ cfu/ml. Goats in group D were immunize and unchallenged and left as control group. All C. pseudotuberculosis infected animals were euthanized humanely 12 weeks post-challenged. Tissue samples such as testes, epididymis, spermatic cord, penis, pituitary gland, mammary gland, vulva, vagina, cervix, uterus, fallopian tube and ovaries were collected for histopathology study. Microscopic examination of all tissues (testes, seminiferous tubules, spermatic cord, penile tissues and the pituitary gland) in the male reproductive organs of the bucks that were inoculated with 2 ml of 0.5% and 1.0% of C. pseudotuberculosis killed vaccine showed normal (animals inoculated with 1.0%) to mild (animals inoculated with 0.5%) histopathological changes when compared with those from group C which showed varying degrees of histopathological changes (p < 0.01) in their various tissues. For the female does, similar histopathological changes were observed for the various tissues examined (ovaries, fallopian tubes, uterine horns, uterine tissues, cervix, vaginal, vulva, mammary glands and the pituitary glands) in which the vaccinated groups A &B showed a significantly (p < 0.001) less histopathological changes when compared with those in group C that showed varying degrees of histopathological changes in the reproductive organs investigated. This study showed the efficacy of C. pseudotuberculosis killed vaccine protecting against reproductive tissue damages cause by the active infection with the live bacteria in both bucks and does in the study area.

Histopathological Lesions Accompanied with First-Time Isolation of a PRRSV-2 Strain in Greece

Genotype 2 strains of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV-2) have been reported sporadically in Europe. Even if, PRRSV-2 reported to be genetically homogenous in Europe due to the introduction of an MLV vaccine strain, independent introductions of PRRSV-2 field strains have been reported. The aim of the present study was to report the complete genome sequence and evaluate the histopathological lesions of a PRRSV-2 strain, isolated for the first time in Greece. During a routine blood sampling in a commercial pig farm, the results revealed positive samples in weaners of 40-60 days for the PRRSV-2, using real-time polymerase chain reaction. The clinical picture was characterized from respiratory symptoms in weaners, as well as coughing and poor performance at finishing stage and less than 3% mortality rate from weaning stage to finishing stage. The use of ORF5 for PRRSV phylogenetic analysis of the isolated PRRSV strain, named "x1544-1 strain", was successfully determined, belonging to the genotype PRRSV-2. Comparison of the obtained sequence revealed nucleotide sequence identity >98% with PRRSV-2 strain VR2332 and other related strains from Denmark and China. The histopathological evaluation revealed diffuse interstitial pneumonia, multifocal interstitial nephritis, while in the lymphoid organs, follicular and paracortical hyperplasia, coexisting with necrosis and depletion of germ cells were detected. The results of current study undersign the importance for veterinary practitioners to have up-to-date access to phylogenetic data linked to phenotypic information to follow-up the control and prevention strategies against PRRSV.

Dietary Probiotic Compound Improves Reproductive Performance of Porcine Epidemic Diarrhea Virus-Infected Sows Reared in a Japanese Commercial Swine Farm under Vaccine Control Condition

Lactogenic immunity transferred to piglets after inoculation of a live vaccine to pregnant sows was proved limited to control porcine epidemic diarrhea (PED). Hence, here we evaluated the efficacy of administration of a probiotic compound containing Bacillus mesentericus, Clostridium butyricum, and Enterococcus faecalis together with a commercial live-attenuated PED vaccine (Nisseiken PED Live Vaccine, Nisseiken, Tokyo, Japan) to improve the health and reproductive performance of PED-infected sows. Twenty pregnant sows in a PED-positive farm were equally divided into probiotics-administered (VP) and control (VC) sow groups. A commercial live-attenuated vaccine was injected as per the manufacturer’s instruction. The probiotic compound (15 g/day) was orally administered to VP from 6 weeks pre-parturition to 7 days post-parturition (ppd7). VP had a significantly higher body weight at ppd7 than VC (191 vs 186 kg; P < 0.05). At day 3 post-parturition (ppd3) (4.18 vs 3.63 kg/day) and ppd7 (5.14 vs 4.34 kg/day), milk produced by VP was significantly (P < 0.05) greater than that by VC. Total immunoglobulin (Ig)A and IgG concentrations at day 0 were significantly (P < 0.05) higher in whey of VP (1.9 and 6.6 g/dL, respectively) than in that of VC (1.7 and 6.1 g/dL, respectively). However, total IgG concentration in whey of VP and VC at ppd3 and ppd7 did not differ. Antibody titer was significantly higher at day 0 in serum of VP than it was that of VC (60 vs 37 in geometric mean; P < 0.05). Likewise, the antibody titer in whey of VP and VC was found to be similar at day 0 (416 vs 208 in geometric mean; P = 0.13). Consequently, VP had fewer days between weaning and return to estrus than did VC (7 vs 10 days; P < 0.05). Moreover, piglets of VP had a significantly (P < 0.05) higher litter weight at birth (9,252 g/litter) and a lower mortality (12%) during suckling than those of VC (8,686 g/litter and 28%, respectively). In summary, probiotic-supplemented, PED-vaccinated sows were healthier, transferred PED-specific antibodies via colostrum to piglets, had greater litter weight at birth, and reduced mortality during suckling.