concanavalin-a and Swine-Diseases

Porcine circovirus 2 (PCV2) is the main pathogen of porcine circovirus diseases and porcine circovirus-associated diseases, which are widespread in swine-producing countries. However, there is controversy regarding the susceptibility of human cells to PCV2 infection. In this study, human cell lines were infected with PCV2 and blind passaged several times. PCV2 entered and replicated in human cells, and infectious virions were generated, indicating that human cell lines were permissive to PCV2 replication. Furthermore, PCV2 replication in human cell lines was enhanced by D-glucosamine or concanavalin A (ConA). However, the infection efficiency of PCV2 was lower in human cells than in PK-15 cells, suggesting that PCV2 infection was limited in human cells. Our study reveals that human cells are permissive for the productive infection of porcine circovirus type 2 in vitro.

Topics: Animals; Cell Line; Circoviridae Infections; Circovirus; Concanavalin A; Glucosamine; Humans; Swine; Swine Diseases; Virus Replication

Dendritic cells (DCs) are professional antigen presenting cells cooperating with other immune cells for the activation of innate and adaptive immune responses. The objective of the present study was to investigate the replication activity of porcine circovirus type 2 (PCV2) in DCs and/or lymphocytes during their cross talk and its possible mechanism. Two models were set, herein. Swine blood monocyte (Mo)-derived DCs (MoDCs) or peripheral blood lymphocytes (PBLs) were inoculated with PCV2 prior to their co-cultivation. Bacterial lipopolysaccharide (LPS) and concanavalin A (Con A) were used to stimulate MoDCs and PBLs, respectively. During 6 days of cultivation, a high PCV2 antigen-containing rate without detectable intranuclear signals and a slight but significant increase in the copy number of PCV2 genome were detected in PCV2-inoculated MoDCs. The presence of LPS alone or PCV2-free PBLs, however, had no effect on the location of PCV2 antigens or copy number of PCV2 genome in PCV2-inoculated MoDCs. On the contrary, active PCV2 replication occurred in Con A-stimulated PCV2-inoculated PBLs. When compared with blood Mos, MoDCs induced significantly higher cell proliferation and intensified PCV2 replication in Con A-stimulated PCV2-inoculated PBLs, for which direct contact between MoDCs and lymphocytes was required. Among the cytokines secreted by Con A-activated PBLs, interleukin (IL)-2, but not IL-4 or interferon-γ, could induce cell proliferation and PCV2 replication in PCV2-inoculated PBLs. The findings suggest that although MoDCs support only limited PCV2 replication in themselves, their accessory cell function is required for cell proliferation and PCV2 replication in PCV2-infected lymphocytes.

Topics: Animals; Cell Proliferation; Circoviridae Infections; Circovirus; Concanavalin A; Dendritic Cells; Flow Cytometry; Fluorescent Antibody Technique, Indirect; Lymphocytes; Real-Time Polymerase Chain Reaction; Swine; Swine Diseases; Virus Replication

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) significantly impact the swine industry worldwide. Co-infections with these viruses are common and several lines of evidence suggest that both PRRSV and PCV2 modify host immune responses that facilitate infection. This study examined cytokine mRNA expression profiles of peripheral blood mononuclear cells (PBMCs) from piglets experimentally co-infected with PRRSV and PCV2 to define the influence of co-infection on host immunity. PBMCs from infected and control piglets were stimulated with concanavalin A and the IL-2, IL-4, IL-6, IL-10, IL-12p40, IFN-gamma and TNF-alpha mRNA levels were determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). PBMCs from PRRSV/PCV2 co-infected piglets had significantly reduced IL-2, IL-4, IL-6, IL-12p40 and IFN-gamma and significantly increased TNF-alpha mRNA levels compared to those of the piglets infected with either PRRSV or PCV2 alone. The IL-10 mRNA levels in all virus-infected groups were significantly up-regulated early during infection. These results suggested that co-infection synergistically suppresses T helper 1 (Th1)-type and Th2-type cytokine production by PBMCs, indicating that co-infection likely compromises cell-mediated and humoral immune responses resulting in increased severity of the diseases in piglets.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Viral; Circoviridae Infections; Circovirus; Concanavalin A; Cytokines; Leukocytes, Mononuclear; Porcine Reproductive and Respiratory Syndrome; Porcine respiratory and reproductive syndrome virus; RNA, Messenger; Swine; Swine Diseases; Up-Regulation

Foot and mouth disease virus (FMDV) is a picornavirus that causes an acute vesicular disease of cloven-hoofed animals. This virus continues to be a threat to livestock worldwide with outbreaks causing severe economic losses. The present study shows an analysis of immune system phenotype and function during the acute phase of FMDV infection in swine. In the first days of infection, a significant lymphopenia is observed that involves all T cell subsets, CD4(+), CD8(+), and CD4(+)/CD8(+). This marked lymphopenia is not a result of active infection of PBMC with the virus. Further, the response of residual peripheral blood T cells to the mitogen, Concanavalin A (ConA) is significantly reduced and occasionally eliminated. Animals usually resolve clinical signs of disease and develop antigen specific T cell responses to the virus and recover ConA reactivity. These characteristics of acute phase infection likely play an important role in viral pathogenesis, propagation and shedding of viral particles and may be targeted as a way of improving vaccine formulations.

Topics: Animals; Blood Cell Count; Concanavalin A; Flow Cytometry; Foot-and-Mouth Disease; Foot-and-Mouth Disease Virus; Lymphocyte Activation; Lymphocyte Subsets; Lymphopenia; Swine; Swine Diseases; T-Lymphocytes; Viremia

Naturally infected cases of swine mycobacteriosis were divided into two groups, localized infection (LI) and disseminated infection (DI). Lymphoproliferative response (LPR) was then examined to estimate their immunological states. Both control and LI groups showed strong response to Concanavalin A (Con A) and phytohemagglutinin (PHA) in the LPR, and lymphocytes recovered from the LI responded well to purified protein derived from M. avium (PPD). On the other hand, the DI group showed weak response to both Con A and PHA, despite their strong response to PPD stimulation. These data suggest that the low LPR to Con A and PHA observed in the DI groups was probably not due to the general unresponsiveness of T-cells.

Topics: Animals; Concanavalin A; Lung; Lymph Nodes; Lymphocyte Activation; Mycobacterium avium; Phytohemagglutinins; Swine; Swine Diseases; Tuberculin; Tuberculosis

The induction of porcine cytokines, which are believed to be important for the regulation of T helper (Th)1- and Th2-specific immune responses of pigs, was analysed after in vitro restimulation with a herpesvirus, Suid herpes 1 (pseudorabies virus [PRV]), in peripheral blood mononuclear cells (PBMC). To this end, quantitative, competitive reverse transcription-polymerase chain reaction (RT-qcPCR) was established using constructed heterologous DNA MIMICS, which contain cytokine- or glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-specific primer-binding sites. This is a simple method that allows reliable determination of the differing regulation of cytokine mRNAs specific for porcine interleukin (IL)-2, -4 and -10, interferon gamma (IFN-gamma) and the housekeeping gene, GAPDH, as an endogenous control. PBMC derived from naive (innate response) and PRV-primed (memory response) outbred swine were analysed comparatively. The results demonstrated that restimulation with PRV significantly enhanced the transcription of Th1-type cytokines (IL-2 and IFN-gamma) but not of Th2-type cytokines (IL-4 and IL-10). This virus-specific cytokine response was only found with PBMC from swine protected against lethal PRV challenge infection, but not with naive PBMC or with PBMC from pigs immunized with plasmid DNA encoding PRV glycoprotein gC. Notably, PBMC derived from immune and naive pigs constitutively produced relatively high amounts of IL-10-specific mRNA, exceeding that of GAPDH mRNA, independently of the addition of viral antigen or the mitogen concanavalin A (Con A). The results of this work should help to provide a better understanding of the effector cell/cytokine network response to infection with, or vaccination against, PRV. Additionally, the simple, reliable and sensitive RT-qcPCR, when used to determine the porcine cytokine pattern, might be of prognostic value for the induction of protective immunity.

Topics: Animals; Cell Culture Techniques; Concanavalin A; Cytokines; Herpesvirus 1, Suid; Immunization; Leukocytes, Mononuclear; Pseudorabies; Pseudorabies Vaccines; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Swine; Swine Diseases; Th1 Cells; Transcription, Genetic; Vaccines, DNA

Living and fixed specimen of Oesophagostomum dentatum were labelled in situ with serum antibodies or a panel of biotin-labelled lectins. Specific binding of antibodies was observed in all parasitic stages--freshly exsheathed 3rd-stage larvae (L3), 3rd- and 4th-stage (L4) larvae cultured in vitro and L3 and L4 and adults isolated from pig intestines. The shedding of the stained layer by motile larvae was inhibited by levamisole-induced paralysis. Larvae cultured in vitro exposed serum-derived proteins on their surface which could be labelled with secondary antibody directed against the respective serum donor species. While freshly exsheathed larvae were recognized by O. dentatum-positive serum only, older larvae and adults cross-reacted with serum from pigs infected with O. quadrispinulatum, a closely related species. Lectin binding varied considerably between stages. While binding was not observed in pre-parasitic stages, Concanavalin A, Soybean Agglutinin, Wheat Germ Agglutinin, Ricinus communis Agglutinin and Peanut Agglutinin bound to developing larvae in varying degrees. Dolichos biflorus Agglutinin only bound to advanced (luminal) larval stages, while adults generally displayed only weak or partial lectin binding (except with Concanavalin A and Wheat Germ Agglutinin). Ulex europaeus Agglutinin only labelled larvae derived from cultures containing 10% pig serum. Cleavage of the carbohydrate residues by sodium periodate treatment resulted in reduction of antibody binding to cultured larvae, but not to freshly exsheathed L3. Concanavalin A, Soybean Agglutinin, and Peanut Agglutinin binding was also reduced by periodate treatment, while binding of Wheat Germ Agglutinin and Ricinus communis Agglutinin was inhibited only in early L3, but not in older stages. The different lectin labelling patterns are related to the different stages of the nematode--infective, invasive, histotropic, and luminal--and may serve as a mode of adaptation for the parasite against the host's immune attack by surface glycoprotein variation, together with antigen shedding (as demonstrated by labelling of motile larvae) and a possible acquisition of host molecules at the parasite's surface. Furthermore, a possible role of this developmental variation in surface carbohydrates in parasite-parasite interactions is discussed.

Topics: Animals; Anthelmintics; Antibodies, Helminth; Antigens, Helminth; Antigens, Surface; Concanavalin A; Epitopes; Gene Expression Regulation, Developmental; Larva; Lectins; Levamisole; Oesophagostomiasis; Oesophagostomum; Peanut Agglutinin; Plant Lectins; Sheep; Soybean Proteins; Swine; Swine Diseases; Wheat Germ Agglutinins

Numerous studies in humans and rats have shown that glutamine supplementation during stressful conditions has favorable outcomes. However, the requirements for glutamine during weaning are unknown. Thus, the effects of glutamine supplementation in healthy and infected weaned pigs were investigated. At 21 d of age, pigs were weaned to an elemental diet supplemented with glutamine (+Gln) or an isonitrogenous diet containing nonessential amino acids (-Gln). At 26 d of age, pigs were intraperitoneally injected with Escherichia coli (+Ecoli) or buffered saline (-Ecoli) and killed at 28 d of age. Infection decreased (P < 0.05) plasma and intramuscular glutamine concentrations, but infected pigs that received +Gln diets had higher intramuscular glutamine levels than those that received -Gln diets. Infected pigs had elevated (P < 0.05) total leukocyte counts, and blood lymphocyte responses ([3H]-thymidine incorporation) to a mixture of phorbol myristate acetate and ionomycin were reduced. White blood cell counts were greater (P < 0.05) in +Gln than -Gln pigs. The peak responses to concanavalin A (Con A) by lymphocytes of +Ecoli+Gln pigs were greater (P < 0.05) than those of +Ecoli-Gln pigs and not different than those of noninfected pigs. Hence, glutamine supplementation maintained muscular glutamine concentrations and normalized lymphocyte function in infected pigs.

Topics: Aging; Amino Acids; Animals; Body Temperature; Carcinogens; Cell Division; Concanavalin A; Diet; Dietary Supplements; DNA; Escherichia coli; Escherichia coli Infections; Glutamine; Immune System; Injections, Intraperitoneal; Ionomycin; Ionophores; Leukocyte Count; Lymphocytes; Muscle, Skeletal; Swine; Swine Diseases; Tetradecanoylphorbol Acetate; Thymidine; Weaning

Seven five-week piglets were infected intranasally with 10(5) TCID50 of porcine reproductive and respiratory syndrome (PRRS) virus strain IAF.exp91. All virus-exposed pigs developed fever, labored abdominal breathing, conjunctivitis, and lymph node enlargement within the first 96 h postexposure (PE), which continued to d 10 to 14 PE. Two pigs that were necropsied at d 7 and 10 PE had diffuse interstitial pneumonitis, cardiopathy and lymphadenopathy. All 5 remaining pigs produced serum IgM and IgG antibodies against PRRS virus by 7 or 14 days PE, as demonstrated by indirect immunofluorescence. This corresponded with the capability of isolating the virus from serum d 7 to d 49 or d 63 PE. Low serum neutralizing antibody titers were detected in 3 of the virus-exposed pigs by 35 days PE. A transient episode of diminished proliferative response of peripheral blood lymphocytes to mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) was observed in the virus-exposed pigs at d 3 PE. However, in vitro spontaneous uptake of [3H]-thymidine was significantly increased in lymphocyte cultures of the same pigs at d 7 or d 14 PE. These results suggest polyclonal activation of peripheral blood lymphocytes.

Topics: Animals; Antibodies, Viral; Antibody Formation; Arterivirus Infections; Concanavalin A; Fluorescent Antibody Technique, Indirect; In Vitro Techniques; Lymph Nodes; Lymphocyte Activation; Phytohemagglutinins; Reference Values; Swine; Swine Diseases; Time Factors

The effect of Ascaris suum infection and treatment with fenbendazole on the blastogenic response of peripheral blood lymphocytes to A. suum antigens and to three phytomitogens was assayed by the lymphocyte transformation technique. Repeated infections with A. suum led to the development of sensitized lymphocytes primarily responding to egg hatching fluid antigen. Treatment with fenbendazole decreased the number of specific sensitized lymphocytes, but favorably increased the resistance of pigs to reinfection. Immunity to reinfection did not correlate with the strength of the blastogenic response to A. suum antigens. Repeated infection with A. suum negatively affected the development of the blastogenic response to phytomitogens in the pigs, leading to a partial depression of the responsiveness of lymphocytes and to the partial suppression by serum. Responses to pokeweed mitogen were affected more than the responses to concanavalin A and phytohemagglutinin.

Topics: Animals; Ascariasis; Concanavalin A; Female; Fenbendazole; Lectins; Lymphocyte Activation; Male; Phytohemagglutinins; Pokeweed Mitogens; Swine; Swine Diseases