Avaliação da carga infectante de Mycoplasma hyopneumoniae e da imunopatologia da fase clínica da Pneumonia Enzoótica em suínos experimentalmente infectados
Carregando...
Arquivos
Data
2019-12-06
Autores
Almeida, Henrique Meiroz de Souza [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Mycoplasma hyopneumoniae é o agente etiológico da Pneumonia Enzoótica Suína (PES), enfermidade de distribuição mundial, e responsável por prejuízos como queda no ganho de peso diário e aumento da susceptibilidade dos animais acometidos a infecções respiratórias secundárias mais graves. Os principais fatores envolvidos na formação de lesão de consolidação crânio-ventral em suínos infectados ainda não são bem elucidados. Sendo assim, este estudo teve como objetivo esclarecer os principais fatores imunológicos e de carga bacteriana envolvidos na formação de lesões macroscópicas, bem como a dinâmica do agente em quatro pontos no tempo da fase aguda da enfermidade em suínos experimentalmente infectados. Para este fim, 24 suínos provenientes de fazenda livre de M. hyopneumoniae foram divididos em dois grupos: controle (n=8) e infectados (n=16). No dia 0 pós-infecção (dpi) os animais do grupo infectado foram inoculados com inóculo de pulmão contendo 106 CCU∕mL de M.hyopneumoniae, pela via intratraqueal, enquanto os animais do grupo controle foram inoculados com 5 mL de meio esterilizado. Semanalmente, os animais foram examinados, pesados e amostras de sangue e suabes nasais foram colhidas. Nos dias 14, 28, 42 e 56 pós-infecção quatro animais infectados e dois controles foram eutanasiados e necropsiados. Durante as necropsias realizou-se o escore de lesão pulmonar macroscópica e foram colhidas amostras biológicas de lesão pulmonar (qPCR e histopatologia), lavado traqueobrônquico (LTB; qPCR) e de três porções anatômicas diferentes de traquéia (qPCR e histopatologia). Amostras de lesão pulmonar também foram coletadas para se analisar a expressão gênica de citocinas envolvidas no processo inflamatório. A quantificação estimada do agente em pulmão mostrou tendência a ser maior nos grupos 42 e 56 dpi, (14 dpi – 1,55 x 103; 28dpi – 8,4 x 103; 42 dpi- 3,2 x 104 e 56 dpi-1,11 x 105) ao contrário do escore de lesão macroscópica (14 dpi – 18,45%, 28dpi – 15,84%, 42 dpi- 7,0% e 56 dpi – 6,25%). A expressão dos genes das citocinas TNF-α, IL-1β, IL-6, IL-8 e INF-γ mostraram-se significativamente correlacionados com a extensão de área de lesão e outros efeitos patológicos como queda no ganho de peso diário. A quantificação estimada do agente na traqueia mostrou um tropismo pela porção mais caudal deste órgão, bem como a quantificação em LTB mostrou que aos 28 dpi a população do agente na árvore brônquica apresentou seu ápice. As alterações patológicas e carga bacteriana analisadas nos períodos evidenciam que a resposta inflamatória do hospedeiro apresentou maior influência na formação de lesões macroscópicas de consolidação crânio-ventral no pulmão do que a quantidade desse patógeno presente nesse órgão ao longo do tempo.
ABSTRACT- Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia (SEP), an infectious respiratory disease reported worldwide and associated with losses in average daily growth and increased susceptibility of infected animals to secondary respiratory infections. The main pathological factors involved in lung macroscopic lesion formation remains not fully understood. Consequently, this study aimed to assess immunopathological factors and M. hyopneumoniae infectant loads in macroscopic lesion formation, and to monitor the pathogen dynamics in four intervals of SEP acute phase in experimentally infected swine. 24 pigs originated from M. hyopneumoniae free farms were divided into two groups: non-infected control (n=8) and infected (n=16). At day 0 post-infection (dpi) animals of infected group were intratracheally inoculated with lung inoculum containing 106 CCU∕mL of M. hyopneumoniae, while noninfected control group was mock infected with sterilized medium. The animals were monitored and weighted and had serum and nasal swabs collected weekly. At 14, 28, 42 and 56 dpi, four animals from the infected group and two of control group were euthanized and necropsied. During necropsy, the lung macroscopic lesion score was assessed and lesion samples (qPCR, histopathology and gene expression) were collected, as well as bronchus alveolar lavage fluid (BALF; qPCR) and trachea samples from three different anatomic sites (qPCR and histopathology). The estimated quantification of the pathogen in lung lesion samples presented a growing trend (14 dpi – 1.55 x 103; 28dpi – 8.4 x 103; 42 dpi- 3.2 x 104 and 56 dpi-1.11 x 105), while the macroscopic lesion score presented an opposite trend (14 dpi – 18.45%, 28dpi – 15.84%, 42 dpi- 7.0% and 56 dpi – 6.25%). The cytokine’s TNF-α, IL-1β, IL-6, IL-8 and INF-γ gene expression were significantly correlated to macroscopic lung lesion score and other pathological effects such as average daily weight gain reduction. The quantification of M. hyopneumoniae in tracheal samples confirmed a higher tropism of the pathogen to the lower part of the respiratory tract, and the quantification in BALF samples showed a pathogen population peak at 28 dpi. The pathological responses and the pathogen load analyzed in the evaluated period showed that the host’s inflammatory response presented higher influence in macroscopic lung lesion formation compared to the bacterial load in the lesion site.
ABSTRACT- Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia (SEP), an infectious respiratory disease reported worldwide and associated with losses in average daily growth and increased susceptibility of infected animals to secondary respiratory infections. The main pathological factors involved in lung macroscopic lesion formation remains not fully understood. Consequently, this study aimed to assess immunopathological factors and M. hyopneumoniae infectant loads in macroscopic lesion formation, and to monitor the pathogen dynamics in four intervals of SEP acute phase in experimentally infected swine. 24 pigs originated from M. hyopneumoniae free farms were divided into two groups: non-infected control (n=8) and infected (n=16). At day 0 post-infection (dpi) animals of infected group were intratracheally inoculated with lung inoculum containing 106 CCU∕mL of M. hyopneumoniae, while noninfected control group was mock infected with sterilized medium. The animals were monitored and weighted and had serum and nasal swabs collected weekly. At 14, 28, 42 and 56 dpi, four animals from the infected group and two of control group were euthanized and necropsied. During necropsy, the lung macroscopic lesion score was assessed and lesion samples (qPCR, histopathology and gene expression) were collected, as well as bronchus alveolar lavage fluid (BALF; qPCR) and trachea samples from three different anatomic sites (qPCR and histopathology). The estimated quantification of the pathogen in lung lesion samples presented a growing trend (14 dpi – 1.55 x 103; 28dpi – 8.4 x 103; 42 dpi- 3.2 x 104 and 56 dpi-1.11 x 105), while the macroscopic lesion score presented an opposite trend (14 dpi – 18.45%, 28dpi – 15.84%, 42 dpi- 7.0% and 56 dpi – 6.25%). The cytokine’s TNF-α, IL-1β, IL-6, IL-8 and INF-γ gene expression were significantly correlated to macroscopic lung lesion score and other pathological effects such as average daily weight gain reduction. The quantification of M. hyopneumoniae in tracheal samples confirmed a higher tropism of the pathogen to the lower part of the respiratory tract, and the quantification in BALF samples showed a pathogen population peak at 28 dpi. The pathological responses and the pathogen load analyzed in the evaluated period showed that the host’s inflammatory response presented higher influence in macroscopic lung lesion formation compared to the bacterial load in the lesion site.
Descrição
Palavras-chave
Doenças infecciosas, Imunologia Veterinária, Citocinas, Expressão gênica, Doenças de suínos, Infectious diseases, Veterinary immunology, Cytokine, Gene expression, Diseases of swine