Histopathological and immunohistochemical findings of swine with spontaneous influenza A infection in Brazil, 2009-2010

Abstract

1148ença altamente contagiosa, de curso rápido e pronta recuperação, causada pelo vírus inϐluenza tipo A (SIV). Os principais sinais clínicos são tosse, febre, anorexia e baixo desenvolvimento. A doença está presente em outros países e, geralmente, está associada com outros agentes infecciosos. No Brasil, a primeira descrição ocorreu em 2011 e foi associada ao vírus H1N1 pandêmico (pH1N1). O principal objetivo deste estudo foi caracterizar as alterações histoló-gicas em casos de doença respiratória suína sugestiva de . It is a highly contagious disease with a rapid course and recovery. The major clinical signs and symptoms are cough, fever, anorexia and poor performance. The disease has been associated with other co-infections in many countries, but not in Brazil, where, however, the ϐirst outbreak has been reported in 2011. The main aim of this study was to characterize the histological features in association with the immunohistochemical (IHC) results for inϐluenza A (IA), porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) in lung samples from 60 pigs submitted to Setor de Patologia Veterinária at the Universidade Federal do Rio Grande do Sul (SPV-UFRGS), Brazil, during 2009-2010. All of these lung samples had changes characterized by interstitial pneumonia with necrotizing bronchiolitis, never observed previously in the evaluation of swine lungs in our laboratory routine. Pigs in this study had showed clinical signs of a respiratory infection. Swine samples originated from Rio Grande do Sul 31 (52%), Santa Catarina 14 (23%), Paraná 11 (18%), and Mato Grosso do Sul 4 (7%). Positive anti-IA IHC labelling was observed in 45% of the cases, which were associated with necrotizing bronchiolitis, atelectasis, purulent bronchopneumonia and hyperemia. Moreover, type II pneumocyte hyperplasia, alveolar and bronchiolar polyp-like structures, bronchus-associated lymphoid tissue (BALT) hyperplasia and pleuritis were the signiϐicant features in negative anti-IA IHC, which were also associated with chronic lesions. There were only two cases with positive anti-PCV2 IHC and none to PRRSV. Therefore, SIV was the predominant infectious agent in the lung samples studied. The viral antigen is often absent due to the rapid progress of SI, which may explain the negative IHC results for IA (55%); therefore, IHC should be performed at the beginning of the disease. This study has shown how important a careful histological evaluation is for the diagnosis. Since 2009, a new histological feature of swine pneumonia in animals with respiratory clinical signs has been observed in samples from pigs with clinical respiratory disease submitted to SPV-UFRGS. In addition, the results proved the importance of histological evaluation for swine herd health management. Brazil, 2009Brazil, -2010 IS e estudar a associação dessas alterações com os resultados de imuno-histoquímica (IHQ) anti-vírus da inϐluenza A (SIV), anti-circovírus suíno tipo 2 (PCV2) e anti-vírus da síndrome reprodutiva e respiratória (...

Porcine respiratory disease complex after the introduction of H1N1/2009 influenza virus in Brazil

“…In this study, almost all cases displayed histologic lesions compatible with IAV infection, suggesting that this virus quickly spread in the naïve pig population and is now established in pig herds of several Brazilian states (Rajao, Costa et al., ; Watanabe et al., ). RT‐qPCR was more sensitive in detecting IAV than VI and IHC.…”

Infectious diseases dynamics in growing/finishing pigs in Southern Brazil (2005-2016)

“…These conditions are usually multifactorial and associated with the interaction between multiple infectious agents, as well as noninfectious cofactors, such as environmental, handling, age, genetics, and nutrition (Rech et al 2018). Swine influenza, which was the main respiratory condition diagnosed in the present study, stood out in Brazil after the human pandemic influenza took place in 2009 concomitantly with a similar clinical disease in pigs, which was caused by similar viral subtypes to the worldwide distributed (Hofshagen et al 2009, Howden et al 2009, Pasma & Joseph 2009, Moreno et al 2010, Pereda et al 2010, Schaefer et al 2011, Watanabe et al 2012, Njabo et al 2012, Holyoake et al 2011. Similarly, in the present study there was a higher frequency of diagnosis between 2010 and 2013, with indexes that reached 43%.…”

Infecção pelo vírus influenza A em suínos no sul de Moçambique

“…Esse tipo de lesão histopatológica é característica da infecção aguda pelos subtipos do VIA adaptados a suínos (H1N1, H1N2 e H3N2) e pelo VIA H1N1pdm2009 (Sreta et al 2009, Pereda et al 2010, Lyoo et al 2014. Assim como descrito em outros estudos (Sreta et al 2009, Watanabe et al 2012, Rajão et al 2013, no exame de IHQ, antígenos de VIA foram visualizados no núcleo de células epiteliais de brônquios e bronquíolos e/ou em macrófagos alveolares. Em 11 amostras de pulmão, imunomarcação para a nucleoproteína do VIA, também foi observada no epitélio de glândulas bronquiais, achado também descrito em suínos (Rajão et al 2013) e em humanos (Nakajima et al 2012) infectados pelo VIA H1N1pdm2009.…”

“…A marcação do VIA na IHQ ocorre, principalmente, na fase aguda da doença (um a cinco dias após a infecção) e a quantidade de antígenos no pulmão está reduzida a partir do sétimo dia após a infecção (Jung et al 2005, Gauger et al 2012, Lyoo et al 2014. Antígenos do VIA foram detectados em suínos com peso vivo entre 5 e 120 kg, o que demonstra que este vírus pode infectar suínos de diferentes faixas etárias, assim como descrito por Watanabe et al (2012) e Rajão et al (2013).…”

“…As lâminas foram contra-coradas com hematoxilina de Harris. Como controle negativo, cortes de pulmão foram incubados com solução fosfatada tamponada (PBS), ao invés de anticorpo primário e para controle positivo foram empregados cortes de pulmão positivos para o VIA (Watanabe et al 2012).…”