Infectious bronchitis corona virus establishes productive infection in avian macrophages interfering with selected antimicrobial functions

• Published in: PloS one Vol. 12; no. 8; p. e0181801
• Main Authors: Amarasinghe, Aruna, Abdul-Cader, Mohamed Sarjoon, Nazir, Sadiya, De Silva Senapathi, Upasama, van der Meer, Frank, Cork, Susan Catherine, Gomis, Susantha, Abdul-Careem, Mohamed Faizal
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.08.2017; Public Library of Science (PLoS)
• Subjects: Animal vaccines; Animals; Antigens; Antiinfectives and antibacterials; Antimicrobial agents; Bacterial infections; Biology and Life Sciences; Biotechnology; Bronchitis; Care and treatment; Cell culture; Chickens; Corona; Coronavirus Infections - immunology; Genome, Viral; Immunization; In vitro methods and tests; Infections; Infectious bronchitis virus; Infectious diseases; Interferon; Lung - pathology; Lungs; Macrophages; Macrophages - immunology; Macrophages - virology; Meat; Meat production; Medical research; Medicine and Health Sciences; Microscopy, Fluorescence; Mortality; Nitric oxide; Nitric Oxide - chemistry; Pathogenesis; Pathology; Poultry; Poultry Diseases - immunology; Poultry Diseases - virology; Proteins; Public health; Replication; Research and Analysis Methods; Respiratory diseases; Respiratory tract; Respiratory tract diseases; Ribonucleic acid; RNA; Trachea; Trachea - pathology; Veterinary medicine; Virology; Viruses; Canada; Calgary Alberta Canada
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0181801

Infectious bronchitis virus (IBV) causes respiratory disease leading to loss of egg and meat production in chickens. Although it is known that macrophage numbers are elevated in the respiratory tract of IBV infected chickens, the role played by macrophages in IBV infection, particularly as a target cell for viral replication, is unknown. In this study, first, we investigated the ability of IBV to establish productive replication in macrophages in lungs and trachea in vivo and in macrophage cell cultures in vitro using two pathogenic IBV strains. Using a double immunofluorescent technique, we observed that both IBV Massachusetts-type 41 (M41) and Connecticut A5968 (Conn A5968) strains replicate in avian macrophages at a low level in vivo. This in vivo observation was substantiated by demonstrating IBV antigens in macrophages following in vitro IBV infection. Further, IBV productive infection in macrophages was confirmed by demonstrating corona viral particles in macrophages and IBV ribonucleic acid (RNA) in culture supernatants. Evaluation of the functions of macrophages following infection of macrophages with IBV M41 and Conn A5968 strains revealed that the production of antimicrobial molecule, nitric oxide (NO) is inhibited. It was also noted that replication of IBV M41 and Conn A5968 strains in macrophages does not interfere with the induction of type 1 IFN activity by macrophages. In conclusion, both M41 and Con A5968 IBV strains infect macrophages in vivo and in vitro resulting productive replications. During the replication of IBV in macrophages, their ability to produce NO can be affected without affecting the ability to induce type 1 IFN activity. Further studies are warranted to uncover the significance of macrophage infection of IBV in the pathogenesis of IBV infection in chickens.