Unusual outcome of in utero infection and subsequent postnatal super-infection with different PCV2b strains / 中国病毒学·英文版

VC2002, isolated from postweaning multisystemic wasting syndrome (PMWS)-affected pig, is a mixture of two porcine circovirus genotype 2b (PCV2b) viruses, K2 and K39. Preliminary experiments disclosed short-term adverse effects of K39, but not K2, on porcine foetuses. These findings led to the hypothesis that infection of immuno-incompetent foetuses with K2 confers a status of immunotolerance, and postnatal super-infection with K39 triggers PMWS. To explore this hypothesis, nine 55-day-old foetuses were inoculated in utero (three with K2-104.3TCID50, three with K39-104.3TCID50 and three with medium), and foeto-pathogenicity examined. At 21 days post-inoculation (dpi), K2 did not induce pathology, whereas pathological effects of K39 were evident. Twenty-four 45-day-old foetuses were subsequently inoculated to examine the long-term effect of K2, including six with K2-high dose-104.3TCID50, six with K2-low dose-102.3TCID50 and 12 mock-inoculated controls. Both doses resulted in ifve mummiifed foetuses and one live-born piglet each (69dpi). K2 was recovered from all mummies. K2 and K2-speciifc antibodies were not detected in serum of the two live-born piglets at birth, indicating full control of K2 infection. The K2-low dose-infected piglet was immunostimulated at day 2, but not the K2-high dose-infected piglet. Both non-stimulated and stimulated K2-infected piglets were super-inoculated with K39 at day 6 or 8 (taken as 0 days post super-inoculation). Low viral replication was observed in the non-stimulated K2-K39 piglet (up to 103.3 TCID50/g;identiifed as K39). In contrast, viral replication was extremely high in the stimulated K2-K39 piglet (up to 105.6TCID50/g) and identiifed as K2, indicating that K2 infection is controlled during foetal life, but emerges after birth upon immunostimulation. However, none of the piglets showed any signs of PMWS.

Expresión de citocinas en cerdos co-infectados con circovirus porcino tipo 2 y el virus del síndrome respiratorio y reproductivo porcino / Cytokine expression in growing pigs co-infected with porcine circovirus type 2 and porcine reproductive and respiratory syndrome virus

The aim of this work was to quantify porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), as well as cytokine mRNA expression (IL-6, IL-12, TNF-α, and IFN-γ) in superficial inguinal lymph nodes (SILN) of pigs from postweaning multisystemic wasting syndrome (PMWS)-affected and healthy farms. Genetic characterization of detected PCV2 sequences was also carried out. Based on the clinical outcome and the quantification of PCV2 nucleic acid by in situ hybridization and real time PCR, pigs were grouped into three categories: 1) PMWS, pigs with signs of wasting and high viral load in SILN (n = 4); 2) wasted-non-PMWS, pigs with signs of wasting and low to intermediate viral loads in SILN (n = 3); and 3) healthy, pigs with no clinical signs and low viral loads (n = 3). PRRSV was detected in three PMWS affected and two-wasted-non-PMWS pigs. The genetic analysis of PCV2 sequences revealed the presence of two genotypes PCV2a and PCV2b in PMWS-affected farms. Cytokine mRNA expression revealed that PMWS affected pigs had low expression of IFN-γ, whereas wasted-non-PMWS pigs showed higher amounts of IFN-γ. These results suggest that an imbalance in cytokines could be involved in the pathogenesis of PMWS.

Los objetivos de este trabajo fueron la cuantificación de circovirus porcino tipo 2 (PCV2) de virus del síndrome respiratorio y reproductivo porcino (PRRSV), así como la expresión de citocinas (IL-6, IL-12, TNF-α, e IFN-γ) en nódulos linfáticos inguinales superficiales (NLIS) de cerdos afectados por el síndrome de desmedro posdestete (postweaning multisystemic wasting syndrome, PMWS) y en cerdos sanos. Con base en el diagnóstico clínico y a la cuantificación de PCV2 por hibridación in situ y qRT-PCR, los cerdos se distribuyeron en tres grupos: 1) PMWS, cerdos con signos de desmedro y con cargas virales altas en NLIS (n = 4); 2) con desmedro sin PMWS, cerdos con signos de desmedro y cargas virales de intermedias a bajas en NLIS (n = 3); y 3) cerdos sanos, sin signos clínicos y con cargas virales bajas (n = 3). El PRRSV fue detectado en tres de los cerdos afectados por el PMWS y en dos cerdos con desmedro, pero sin el síndrome. Se caracterizaron las secuencias nucleotídicas del ORF2 de los PCV2 encontrados y los análisis genéticos revelaron la presencia de 2 genotipos PCV2a y PCV2b en las granjas afectadas con el PMWS. El perfil de expresión de citocinas mostró una baja expresión de IFN-γ en los cerdos con PMWS, mientras que los cerdos con desmedro sin PMWS mostraron valores elevados de esta citocina. Estos resultados sugieren que existe un desbalance en la producción de citocinas que puede estar implicado en la patogénesis de la enfermedad.

Prevalence of porcine parvovirus in pigs with postweaning multisystemic wasting syndrome in Jeju Island / 대한수의학회지

Postweaning multisystemic wasting syndrome (PMWS), which was first identified in western Canada in 1991 and more recently in the United States, Europe and Asia, is an emerging disease in pigs. Porcine circovirus type 2 (PCV-2) is the primary infectious viral agent causing PMWS, but the full expression of the disease may require the presence of other agents. It is reported that there is apparent synergism between PCV-2 and porcine parvovirus (PPV) in increasing the severity of the clinical signs and lesions of PMWS. From January 2006 to May 2008, a total of the 154 lymph node samples were collected from 4~12 weeks old pigs which had been submitted to the College of Veterinary Medicine, Jeju National University, Korea. These pigs were diagnosed as PMWS on the basis of clinical and pathological examination from 48 commercial herds in Jeju Island. Based on the immunohistochemistry, porcine parvovirus was detected in 69 cases (44.8%) from 154 weaned or grower pigs. PPV antigens were detected in the cytoplasm of histiocytic cells multifocally infiltrated in the cortex and paracortex of lymph nodes. The results of this study clarify that PPV is prevalent in pigs with PMWS on Jeju Island. Therefore PPV is one of the most important co-agents in the development of naturally acquired PMWS. This study may be helpful to the control of this disease and to epidemiological aspects.

Gastric ulcers in pigs affected with postweaning multisystemic wasting syndrome / Úlceras gástricas em suínos afetados pela síndrome multissistêmica do definhamento

Samples of gastric lymph nodes and the stomachs from 24 pigs selected from herds affected by postweaning multisystemic wasting syndrome (PMWS) and sudden death associated with gastric ulcers were studied. Pigs were selected on the basis of unthriftiness, decreased feed intake, and wasting. The stomachs were opened, inverted, and classified into 0-3 score according the severity of the gross lesions present in pars oesophagica (non-glandulargastric mucosa). Selected samples were processed for paraffin embedding and stained with hematoxylin and eosin. Immunohistochemistry using anti-PCV2 (porcine circovírus type 2) antibody, anti-Helicobacter pylori antibody and a wide-spectrum anti-cytokeratin antibody was performed. Gross changes in pars oesophagea were classified according to the severity of lesions as score 3, 2, and 1 in 8, 6, 5 stomachs respectivelly. Microscopically, hyperplastic lymphoid follicles, lymphohistiocytic inflammatory infiltrates and focci of necrosis in the gastric mucosa were common findings. Large amounts of PCV2 antigen were observed in the cytoplasm and nuclei from intralesional cells and debris from the gastric glandular mucosal zone; however, in the fundus, anti-PCV2 immunostaining was restricted to the surface mucosal cells and foveolar compartment. All gastric lymph nodes were positive for PCV2 antigen. Anti-H. pylori immunostaining was seen in eleven cases, mainly in the antrum, on the mucosal surface and foveolar compartment. The association of the anti-PCV2 immunostaining with the glandular mucus-producing cells suggests a role for PCV2 as an additional factor for the swine ulcer development.(AU)

Amostras de linfonodos gástricos e os estômagos de 24 leitões selecionados de rebanhos afetados pela síndrome multissistêmica do definhamento suíno e mortes súbitas por úlceras gástricas foram estudados. Os animais foram seleciona dos por baixa performance, baixo consumo de alimento e desnutrição. Os estômagos foram abertos, invertidos e classificados, conforme a severidade das lesões presentes na pars oesophagica (porção não-glandular da mucosa gástrica). Amostras selecionadas foram processadas por método histológico convencional para coloração de hematoxilina-eosina. Testes imuno-histoquímicos utilizando anticorpos anti-PCV2 (circovírus suíno tipo 2), anti-Helicobacter pylori e anticitoqueratina de largo espectro foram feitos. As alterações macroscópicas na pars oesophagica foram classificadas como de escore 3, 2 e 1 respectivamente em 8, 6 e 5 estômagos. Microscopicamente, foram notados folículos linfóides hiperplásicos, infiltrados linfohistiocitários e focos de necrose na mucosa gástrica. Grandes quantidades de antígeno do PCV2 foram observadas no citoplasma, núcleo e restos necróticos de células intralesionais das glândulas gástricas nas regiões do antro e cárdia; entretanto, na região do fundo, a marcação anti-PCV2 foi restrita às células da superfície mucosa e fossetas gástricas. Todos os linfonodos gástricos foram positivos para PCV2. Coloração anti-H. pylori foi identificada em 11 casos, principalmente, na superfície mucosa e fossetas gástricas no antro. A associação de antígenos PCV2 com células produtoras de muco lesadas na zona glandular gástrica sugere o envolvimento de PCV2 como um fator adicional para o desenvolvimento da úlcera gástrica suína.(AU)

Associação entre otites bacterianas e infecção pelo circovírus suíno tipo 2 (PCV2) em suínos / Association between bacterial otitis and porcine circovirus 2 (PCV2) infection in pigs

Neste trabalho, foi estudada a ocorrência e a bacteriologia das otites purulentas em suínos apresentando três condições clínico-patológicas distintas: síndrome multissistêmica do definhamento dos suínos (SMDS), crescimento retardado (porém sem apresentação de sinais clínicos da SMDS) e crescimento normal. No total, foram examinados 385 animais com idade de 60-130 dias, sendo a confirmação do diagnóstico da SMDS obtida pelos sinais clínicos e achados patológicos e pela detecção de antígenos virais por imunoistoquímica. De 242 animais com a SMDS, 57 (23,5 por cento) apresentaram lesões purulentas no ouvido médio. Entre os 119 animais de baixo desenvolvimento, apenas 1 (0,7 por cento) apresentou a lesão. Não foram detectadas lesões macroscópicas no ouvido médio dos 24 animais com crescimento normal. Os agentes isolados com maior freqüência foram Arcanobacterium pyogenes (43 por cento), Streptococcus α-hemolíticos (37,2 por cento) e Pasteurella multocida (27,9 por cento) dos 86 ouvidos submetidos à bacteriologia. A alta ocorrência de lesões purulentas no ouvido médio de animais com a SMDS sugere que a infecção pelo PCV2 pode tornar o suíno mais suscetível às otites bacterianas. A ocorrência reduzida dessas lesões em suínos de baixo desenvolvimento, sem a manifestação clínica da SMDS, sugere que a otite média não representa uma causa importante de mau desempenho em leitões nas fases de crescimento e terminação. O envolvimento de A. pyogenes, Streptococcus α-hemolíticos e P. multocida na maioria das lesões apontam a importância desses organismos como agentes causais de otite média em suínos.(AU)

The occurrence and bacteriology of purulent otitis in groups of pigs affected by three different clinical conditions are described: postweaning multisystemic wasting syndrome (PMWS), depressed growth (attrition) and normal growth (control). A total of 385 animals, 60-130 days of age, were examined. Diagnosis of PMWS was confirmed by the presence of clinical signs and pathological findings compatible with the disease, and through detection of viral antigens in tissues by immunohistochemistry. From 242 pigs with PMWS, 57 (23.5 percent) showed purulent lesions in the middle ear. Among 119 pigs with attrition, only 1 (0.7 percent) presented the lesion. In 24 control pigs, middle ear lesions were not detected. The most frequently isolated agents from the lesions were Arcanobacterium pyogenes (43 percent), á-hemolytic Streptococci (37.2 percent) and Pasteurella multocida (27.9 percent) out of 86 materials. The frequent occurrence of purulent lesions in the middle ear of PMWS affected pigs suggests that PCV2 infection may increase the susceptibility to bacterial otitis. The low occurrence of this disease in piglets with attrition suggests that otitis does not represent a significant cause for depressed growth in pigs from growing and finishing age. The isolation of A. pyogenes, á-hemolytic Streptococci and P. multocida from most of the lesions emphasizes the importance of these organisms as causal agents of otitis media in swine.(AU)

Perfil sorológico para circovírus suíno tipo 2 em granjas comerciais de suínos no Brasil / Serological profiles to porcine circovirus type 2 antibodies in Brazil

A técnica de imunoperoxidase em monocamada de células (IPMC) para demonstração de anticorpos contra o circovírus suíno tipo 2 (CVS2) foi empregada para a investigação sorológica em oito granjas de suínos destinadas à produção comercial. Das 240 amostras de soros testadas, 229 (95,4%) foram reagentes com títulos que variaram de 20 até 10.240. Títulos de anticorpos foram detectados nas faixas etárias de duas a três semanas até animais acima de 24 semanas e encontrados em granjas com e sem a síndrome multissistêmica do definhamento (SMD). A média dos títulos de anticorpos revelou diferenças estatísticas (P<0,05) nas faixas etárias de 11 a 13 e 14 a 22 semanas nos animais oriundos de granjas com e sem a SMD. Os resultados refletem a importância de conhecer o perfil sorológico do rebanho e assegurar a implantação de um efetivo cronograma de vacinação contra o CVS2.

The immunoperoxidase in monolayer cells (IPMC) technique for the demonstration of antibodies against type 2 porcine circovirus (PCV2) was used for the serological investigation in eight industrial swine farms. Out of the 240 tested sera, 229 (95,4%) were reactive with titers which varied from 20 up to 10.240. Titers of antibodies were detected in pigs from two to three weeks of age up to above 24 weeks of age, and were observed in farms with and without clinical signs indicative of the post-weaning multisystemic wasting syndrome (PMWS). Analysing the mean titers, statistical differences (P<0.05) were evidentiated in two age intervals, of 11 to 13 and 14 to 22 weeks of age. The results indicate the importance of determining the serological profiles of commercial swine herds, in order to enable the implantation of effective hygiene and vaccination protocols for PCV2 prevention.

Abscessos dentários periapicais em leitões com síndrome multissistêmica do definhamento / Dental periapical abscesses in piglets affected by postweaning multisystemic wasting syndrome PMWS

Duzentos e oitenta leitões, entre 40 e 70 dias de idade, afetados pela sindrome multissistêmica do definhamento (SMD) foram examinados após eutanásia para pesquisa de lesões dentárias. Pelo menos um abscesso periapical foi observado em 58 leitões (20,7 por cento), dos quais 12 apresentaram abscessos múltiplos. Terceiros incisivos superiores, 3os incisivos inferiores, caninos superiores, caninos inferiores e outros dentes apresentaram respectivamente 22 (31,4 por cento), 16 (22,9 por cento), 4 (5,7 por cento), 23 (32,9 por cento) e 5 (7,1 por cento) abscessos periapicais. A maior prevalência de abscessos observada nos dentes 3os incisivos e caninos inferiores está provavelmente associada com a maior área de corte ou desgaste que sofrem esses dentes. Entre as bactérias isoladas de amostras de 65 abscessos, Streptococcus sp. foi a mais prevalente e esteve presente em 21,48 por cento e 27,7 por cento dos isolados em aerobiose e anaerobiose, respectivamente. Na segunda posição em prevalência estiveram as bactérias corineformes, as quais foram mais freqüentemente isoladas em atmosfera anaeróbica do que aeróbica. Houve preponderância de isolamentos de bactérias Gram-positivas. Não foi possível determinar se as co-infecções bacterianas predispuseram às lesões características de SMD ou foram conseqüentes à imunossupressão causada pela infecção com PCV2.

Swine producers have historically resected needle teeth of newborn pigs to prevent potential injuries to the sow mammary gland and faces of littermates. However, the possible impact of this practice on pig performance has been questioned. As part of a study, 280 PMWS affected piglets, with 40-70 days of age, were examined for the presence of dental lesions immediately after euthanasia. Most pigs were confirmed as PMWS by the detection of typical microscopic lesions and immunohistochemical pattern. At least one periapical abscess was observed in 58 piglets (20.7 percent), of which 12 had multiple abscesses. There were 22 (31.4 percent), 16 (22.9 percent), 4 (5.7 percent), 23 (32.9 percent), and 5 (7.1 percent) abscesses in 3rd upper incisives, 3rd lower incisives, upper canines, lower canines, and other teeth, respectively. The higher prevalence of dental abscesses observed in 3rd incisives and lower canines is probably associated with the wider area of grinding or clipping to which these teeth were subjected. Among bacteria isolated from samples collected from 65 abscesses, Streptococcus sp. was the most prevalent bacteria and was present in 21.48 percent and 27.7 percent of the aerobic and anaerobic isolates, respectively. In the second most frequent group were coryneform microorganisms, which showed higher rate of isolation under anaerobic atmosphere than in aerobic culture. There was preponderance of Gram-positive isolates. It could not be determined whether these bacterial co-infections predisposed pigs to development of PMWS-type lesions or if were subsequent to the PCV2 infection.

Intestinal lesions in pigs affected with postweaning multisystemic wasting syndrome / Lesões entéricas em suínos afetados por síndrome multissistêmica do definhamento dos suínos

Samples of mesenteric lymph nodes and intestines from 79 unthrifty 3- to 5-month-old postweaning pigs, confirmed as naturally affected with postweaning multisystemic wasting syndrome (PMWS), were studied. Pigs originated from 12 farms in southern Brazil and were selected on the basis of clinical signs and/or gross lesions suggestive of enteric disorder. Lymphohistiocytic infiltrates of varying intensity were associated with anti-porcine circovirus type 2 (anti-PCV2) immunostaining (IS) in samples of intestines and mesenteric lymph nodes from all pigs. Although most findings were similar to those described in PCV2-associated enteritis, anti-PCV2 IS in association with depletion of the goblet cell mucin stores (24 pigs), diffuse ileal villous atrophy and fusion (18 pigs), and dilatation of the lymphatic vessels (11 pigs) combined or not with lymphangitis were also observed. PCV2 antigen was immunohistochemically demonstrated in the cytoplasm and nuclei from intralesional epithelial cells, histiocytes, and endothelial-like cells in intestinal tissues. Together these findings imply an association with PCV2. The presence of co-infections by Lawsonia intracellularis, Brachyspira spp., Mycobacterium spp., Salmonella spp., rotavirus, parvovirus, coronavirus and enteric calicivirus with PCV2 in the intestinal lesions was investigated.

Amostras de linfonodos mesentéricos e intestinos de 79 leitões desmamados refugos, entre 3 e 5 meses de idade e confirmados como naturalmente afetados pela síndrome multissistêmica do definhamento foram estudadas. Os suínos eram oriundos de 12 criações no sul do país e foram selecionados em função dos sinais clínicos e/ou lesões macroscópicas sugestivos de doença entérica. Infiltrados linfoistiocíticos de intensidades variáveis foram associados com marcação positiva anti-circovirus suíno tipo 2 (anti-PCV2) em amostras de intestinos e linfonodos mesentéricos de todos os 79 animais. Embora a maioria dos achados fossem semelhantes aos descritos em enterite associada com PCV2, marcação imuno-histoquímica anti-PCV2 foi associada com depleção de células caliciformes (24 suínos), atrofia e fusão de vilosidades do íleo (18 suínos) e dilatação de vasos linfáticos (11 suínos) combinada ou não com linfangite. Antígenos de PCV2 foram demonstrados por imuno-histoquímica no citoplasma e núcleo de células epiteliais intralesionais, histiócitos e células tipo endotelial em tecidos intestinais. Em conjunto, esses resultados sugerem que as lesões estavam associadas com PCV2. A presença de co-infecções por Lawsonia intracellularis, Brachyspira spp., Mycobacterium spp., Salmonella spp., rotavírus, parvovírus, coronavírus e calicivírus entérico com PCV2 nas lesões intestinais foi investigada.