Productive replication of nephropathogenic infectious bronchitis virus in peripheral blood monocytic cells, a strategy for viral dissemination and kidney infection in chickens

Abstract

In the present study, the replication kinetics of nephropathogenic (B1648) and respiratory (Massachusetts-M41) IBV strains were compared in vitro in respiratory mucosa explants and blood monocytes (KUL01+ cells), and in vivo in chickens to understand why some IBV strains have a kidney tropism. B1648 was replicating somewhat better than M41 in the epithelium of the respiratory mucosa explants and used more KUL01+ cells to penetrate the deeper layers of the respiratory tract. B1648 was productively replicating in KUL01+ monocytic cells in contrast with M41. In B1648 inoculated animals, 102.7–6.8 viral RNA copies/100 mg were detected in tracheal secretions at 2, 4, 6, 8, 10 and 12 days post inoculation (dpi), 102.4–4.5 viral RNA copies/mL in plasma at 2, 4, 6, 8, 10 and 12 dpi and 101.8–4.4 viral RNA copies/106 mononuclear cells in blood at 2, 4, 6 and 8 dpi. In M41 inoculated animals, 102.6–7.0 viral RNA copies/100 mg were detected in tracheal secretions at 2, 4, 6, 8 and 10 dpi, but viral RNA was not demonstrated in plasma and mononuclear cells (except in one chicken at 6 dpi). Infectious virus was detected only in plasma and mononuclear cells of the B1648 group. At euthanasia (12 dpi), viral RNA and antigen positive cells were detected in lungs, liver, spleen and kidneys of only the B1648 group and in tracheas of both the B1648 and M41 group. In conclusion, only B1648 can easily disseminate to internal organs via a cell-free and -associated viremia with KUL01+ cells as important carrier cells.

Attenuated live infectious bronchitis virus QX vaccine disseminates slowly to target organs distant from the site of inoculation

“…The ability of a virus to infect and replicate in tissues beyond the site of infection depends on the route of transport and the susceptibility of a respective organ. Since the 1960s, viremia has been proposed as one of the routes of IBV dissemination [18], with only recent evidence for involvement of mononuclear cells in transportation of the virus throughout the body [19,20]. In our study, mononuclear cells expressing viral proteins were only rarely detected (data not shown), so it is yet unclear whether they truly contribute to IBV dissemination.…”

Infectious Bronchitis

“…Some of these factors known to exacerbate the clinical disease have been used in experimental models to evaluate the clinical outcome of interaction between such factors and different IBV strains. Reddy et al (154) reported significant differences between the replication kinetics of the nephropathogenic B1648 and respiratory M41 IBV strains when compared in vitro in respiratory mucosa explants and blood monocytes (KUL01(+) cells), and in vivo in chickens that might explain the different behavior of these strains in chickens.…”

Chicken mannose binding lectin has antiviral activity towards infectious bronchitis virus

“…Interestingly, serum cMBL showed an acute response during IBV infection with an approximately two-fold increase in concentration (Juul-Madsen et al, 2011;Nielsen et al, 1998Nielsen et al, , 1999. As transport of IBV from the primary site of infection to other target organs has been suggested to occur via viremia (McFerran and McNulty, 1993;Reddy et al, 2016), it might well be that MBL is able to interact directly with IBV in the blood during transport to other target organs.…”