Características hematológicas y patológicas de cerdos inoculados experimentalmente con el aislado chileno del virus síndrome respiratorio y reproductivo porcino

Ramírez, E; Ruiz, A; Islas, Armando; Lecocq, C; Carrasco, L.; Quezada, M.

doi:10.4067/s0301-732x2006000200009

Cited by 3 publications

(3 citation statements)

References 24 publications

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“…Because of the postulated notion that the outbreaks of PRRSV in Chile could involve certain PRRSV strains of unusual attenuation and limited dissemination (Ruiz et al., 2003), this study was designed to better understand how a typical Chilean isolate behaves from the point of view of its shedding and its capacity for transmission by direct contact as it might occur under field conditions. Previous experimental studies (Quezada et al., 2004; Ramírez et al., 2004, 2006) suggested that the Chilean PRRSV might behave differently from some of the other US isolates of greater pathogenicity, such as those described by Rossow et al. (1994, 1995), Halbur et al.…”

Section: Discussionmentioning

confidence: 97%

“…Because of the postulated notion that the outbreaks of PRRSV in Chile could involve certain PRRSV strains of Nasal 0/5 3/5 4/5 4/5 4/5 4/5 0/5 0/5 1/5 1/5 Ocular 0/5 0/5 5/5 2/5 3/5 2/5 0/5 0/5 0/5 0/5 Saliva 0/5 0/5 0/5 4/5 2/5 4/5 2/5 2/5 1/5 2/5 Faeces 0/5 0/5 2/5 1/5 3/5 4/5 0/5 0/5 0/5 0/5 unusual attenuation and limited dissemination (Ruiz et al, 2003), this study was designed to better understand how a typical Chilean isolate behaves from the point of view of its shedding and its capacity for transmission by direct contact as it might occur under field conditions. Previous experimental studies (Quezada et al, 2004;Ramírez et al, 2004Ramírez et al, , 2006 suggested that the Chilean PRRSV might behave differently from some of the other US isolates of greater pathogenicity, such as those described by Rossow et al (1994Rossow et al ( , 1995, Halbur et al (1995Halbur et al ( , 1996b and Rossow et al (1999), with a shorter viraemia and a multisystemic viral distribution although with lesions of lesser intensity. In this study the pigs behaved similarly to previous studies, with only slight and non-specific symptoms being detected in the group of inoculated animals and in all the contact groups without the presence of evident respiratory symptoms.…”

Section: Discussionmentioning

confidence: 97%

“…Little is known about the level of pathogenicity and virulence of the PRRSV strains acting in Chile. The reference Chilean isolate was used by us for experimental inoculation demonstrating that the virus disseminates through the body producing mild lesions at low frequency and in an inconsistent pattern, in comparison to other US PRRSV strains, thus leading to the notion that the Chilean isolates of PRRSV could be of lower pathogenicity (Quezada et al., 2004; Ramírez et al., 2006). Considering that several of the Chilean isolates collected so far are genetically similar (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Pathogenicity and Transmissibility of a Chilean Isolate of Porcine Reproductive and Respiratory Syndrome Virus

Ramírez¹,

Moreno²,

Díaz³

et al. 2008

Transboundary and Emerging Diseases

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The objective of this study was to determine clinical features, shedding and transmission of a Chilean Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) strain upon experimental inoculation of 4-week-old pigs. Six groups of five animals each were used. The G1 (donor) group was inoculated with PRRSV, maintained in an isolation unit for 35 days, and sampled daily to determine shedding in mucosal secretions and faeces, viraemia and seroconversion. An uninfected control group (G6) was equally maintained and sampled under strict isolation. Four other groups (G2 to G5) were exposed to PRRSV via direct contact with G1 for 5-day periods in a staggered manner, throughout the 35-day period, and were later placed in an independent isolation unit to monitor infection status for 7 days. All the animals in G1 and G6 were killed at 35 days post-inoculation (dpi) and the contact groups at 12 days post-contact (dpc). Samples were obtained from diverse organs for histopathological, immunohistochemical (IHC) and virological analysis. No clinical symptoms were evident in any group, except for a transient fever observed in G1. Histopathologically, all the animals of G1 had interstitial pneumonia, although scarce PRRSV-positive cells were detected in the lung using IHC. PRRSV-positive cells (IHC) were detected in the lymphoid tissue of all animals in infected groups, but especially in G3 and G4. Viraemia was detected in G1 (3-35 dpi) and in the all contact groups (5-12 dpc). Likewise, ranging from 3 to 19 dpi, PRRSV was detected in at least one animal from the tonsils and lungs in all infected groups, in nasal and ocular secretions, saliva or faeces. These results indicate that the donor group excreted infectious PRRSV and was able to transmit the infection to susceptible pigs. The critical shedding period was 7-19 dpi, during which, most likely, transmission took place.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Pathogenicity and Transmissibility of a Chilean Isolate of Porcine Reproductive and Respiratory Syndrome Virus

Ramírez¹,

Moreno²,

Díaz³

et al. 2008

Transboundary and Emerging Diseases

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Evaluación de la transmisión y capacidad de infección por contacto directo desde cerdos inoculados experimentalmente con el aislado chileno del virus síndrome respiratorio y reproductivo porcino

Ramírez¹,

Quintana²,

Ruiz³

et al. 2007

Arch. med. vet.

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SUMMARYThe objective of this study was to determine the infectiousness and transmission capacity of the Chilean isolate of the PRRS virus to swine susceptible via direct contact. Therefore, 30 pigs, divided into 6 groups of 5 animals each, were used, one of which (G1) was inoculated with the virus and maintained in isolation unit 1 for 35 days, during which period blood samples were taken at 0, 3, 7, 11, 15, 19, 23, 27, 31 and 35 days post infection (dpi) for haemogram and viral isolation. Another group (G6) was used as a control and maintained in isolation unit 3. The remaining groups (G2, G3, G4, G5) were exposed by direct contact to the animals of G1 between 3 to 7, 10 to 14, 17 to 21, and 24 to 28 dpi, respectively, and later were taken to isolation unit 2 for 7 days. These animals were sampled for the viral isolate and haemograms at 0, 5 and 12 days post contact (dpc). At slaughter of G1 and G6 (35 dpi) and the contact groups (12 dpc) samples were collected from nasal mucous, tonsils, submandibular lymph node, lung and spleen for histopathological and immunohistochemical (IHC) study and samples of the tonsils and lungs for viral isolation. Only the pigs of G1 had a transitory fever and neither respiratory symptoms nor alterations in the haematological parameters were registered in the pigs of all groups. At necropsy, lymphadenopathy was observed in all the groups. Histopathologically, all the pigs of G1 had interstitial pneumonia, although via IHC few immunostained cells were detected. In lymphatic tissues, hyperplasia and lymphatic necrosis were observed. In all the pigs, cells positive to IHC were detected, especially in G3 and G4. The virus was isolated from blood between 3 and 23 dpi in G1, and between 5 and 12 dpc in G2 and G3; however it was not isolated from the serum of G4 and G5. The virus was isolated from the tonsils of all the pigs of G1 and the contact groups, although it was not isolated from the lungs in G4. These results indicate that the inoculated pigs are capable of transmitting the disease to susceptible pigs, including in the absence of viremia during a period of 28 days.Palabras clave: síndrome respiratorio y reproductivo porcino, transmisión, infección.

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Estudios hematológicos y patológicos comparativos de cerdos inoculados con un aislado de campo y el serotipo 5 ATCC de Actinobacillus pleuropneumoniae

Muñoz¹,

Ruiz²,

González³

et al. 2010

Arch. med. vet.

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Actinobacillus pleuropneumoniae (App) es una bacteria cocobacilar, Gram negativa, encapsulada, hemolítica y anaerobia facultativa de la familia Pasteurellaceae (Vadillo y col 2002) y agente etiológico de la pleuroneumonía contagiosa porcina (PCP), una de las enfermedades bacterianas más importantes del complejo respiratorio porcino (Losinger 2005). La transmisión de la enfermedad ocurre por la introducción de animales portadores, que diseminan App a través del aire, ya sea por gotas de aerosol o por el contacto directo entre los cerdos (Jacobsen y col 2005). En cuanto a la patogenicidad y virulencia de App, se ha observado que los serotipos 1, 5, 9 y 11 son los más virulentos (Haesebrouck y col 1997). Sin embargo, se debe señalar que cualquier serotipo puede causar cuadros sobreagudos, dependiendo del perfil de expresión y secreción de toxinas Apx (I, II, III, IV), el cual es distinto en cada serotipo (Dreyfus y col 2004), existiendo así una asociación entre el serotipo y los brotes que se presentan en un plantel porcino (Gottschalk 1998). En cuanto a las alteraciones hematológicas observadas en cerdos con cuadro agudo o crónico de PCP, Kiorpes y col (1990) detallan cambios drásticos en el leucograma, Estudios hematológicos y patológicos comparativos de cerdos inoculados con un aislado de campo y el serotipo 5 ATCC de Actinobacillus pleuropneumoniae # Comparative hematological and pathological study of inoculated pigs with a field isolate and an ATCC serotype 5 of Actinobacillus pleuropneumoniae

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Características hematológicas y patológicas de cerdos inoculados experimentalmente con el aislado chileno del virus síndrome respiratorio y reproductivo porcino

Cited by 3 publications

References 24 publications

Evaluation of the Pathogenicity and Transmissibility of a Chilean Isolate of Porcine Reproductive and Respiratory Syndrome Virus

Evaluation of the Pathogenicity and Transmissibility of a Chilean Isolate of Porcine Reproductive and Respiratory Syndrome Virus

Evaluación de la transmisión y capacidad de infección por contacto directo desde cerdos inoculados experimentalmente con el aislado chileno del virus síndrome respiratorio y reproductivo porcino

Estudios hematológicos y patológicos comparativos de cerdos inoculados con un aislado de campo y el serotipo 5 ATCC de Actinobacillus pleuropneumoniae

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