Co-infection between influenza virus and flagellated bacteria Co-infecção entre vírus influenza e bactéria flagelada

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Dalva Assunção Portari Mancini, Rita Maria Zucatelli Mendonça, Andrea Luppi Fernandes Dias, Ronaldo Zucatelli Mendonça, José Ricardo Pinto
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 2005
• Subjects: Stenotrophomonas maltophilia; Influenza virus; Co-infections in vitro; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic; Entrada
• Online Access: https://doi.org/10.1590/S0036-46652005000500007; https://doaj.org/article/78287e150bf44bab95dfe9bd48228afd

Trypsin is required in the hemagglutinin (HA) cleavage to in vitro influenza viruses activation. This HA cleavage is necessary for virus cell entry by receptor-mediated endocytosis. Bacteria in the respiratory tract are potential sources of proteases that could contribute to the cleavage of influenza virus in vivo. From 47 samples collected from horses, pigs, and from humans, influenza presence was confirmed in 13 and these samples demonstrated co-infection of influenza with flagellated bacteria, Stenotrophomonas maltophilia from the beginning of the experiments. Despite treatment with antibiotics, the bacteria remained resistant in several of the co-infected samples (48.39%). These bacteria, considered opportunistic invaders from environmental sources, are associated with viral infections in upper respiratory tract of hosts. The protease (elastase), secreted by Stenotrophomonas maltophilia plays a role in the potentiation of influenza virus infection. Proteolytic activity was detected by casein agar test. Positive samples from animals and humans had either a potentiated influenza infectivity or cytopathic effect (CPE) in MDCK and NCI H292 cells, Stenotrophomonas maltophilia were always present. Virus and bacteria were observed ultrastructurally. These in vitro findings show that microbial proteases could contribute to respiratory complications by host protease activity increasing inflammation or destroying endogenous cell protease inhibitors. Tripsina é necessária na ativação da clivagem do vírus influenza A in vitro. Esta clivagem é importante para entrada do vírus na célula por endocitose mediada pelo receptor celular. Bactérias presentes no trato respiratório são fontes de proteases que podem contribuir na replicação do vírus influenza in vivo. Entre 47 amostras coletadas de cavalos, suínos e humanos, a influenza foi isolada e confirmada em 13 que estavam co-infectadas com bactéria flagelada: Stenotrophomonas maltophilia desde o início destes experimentos. Apesar do tratamento das amostras com antibióticos, ...