Avian metapneumovirus infection of chicken and turkey tracheal organ cultures: comparison of virus–host interactions

Abstract

Avian metapneumovirus (aMPV) is a pathogen with worldwide distribution, which can cause high economic losses in infected poultry. aMPV mainly causes infection of the upper respiratory tract in both chickens and turkeys, although turkeys seem to be more susceptible. Little is known about virus-host interactions at epithelial surfaces after aMPV infection. Tracheal organ cultures (TOC) are a suitable model to investigate virus-host interaction in the respiratory epithelium. Therefore, we investigated virus replication rates and lesion development in chicken and turkey TOC after infection with a virulent aMPV subtype A strain. Aspects of the innate immune response, such as interferon-α and inducible nitric oxide synthase mRNA expression, as well as virus-induced apoptosis were determined. The aMPV-replication rate was higher in turkey (TTOC) compared to chicken TOC (CTOC) (P < 0.05), providing circumstantial evidence that indeed turkeys may be more susceptible. The interferon-α response was down-regulated from 2 to 144 hours post infection in both species compared to virus-free controls (P < 0.05); this was more significant for CTOC than TTOC. Inducible nitric oxide synthase expression was significantly up-regulated in aMPV-A-infected TTOC and CTOC compared to virus-free controls (P < 0.05). However, the results suggest that NO may play a different role in aMPV pathogenesis between turkeys and chickens as indicated by differences in apoptosis rate and lesion development between species. Overall, our study reveals differences in innate immune response regulation and therefore may explain differences in aMPV -A replication rates between infected TTOC and CTOC, which subsequently lead to more severe clinical signs and a higher rate of secondary infections in turkeys.

New Insights into the Host–Pathogen Interaction of Mycoplasma gallisepticum and Avian Metapneumovirus in Tracheal Organ Cultures of Chicken

“…During mono-infections, both AMPV and M. gallispeticum show a similar tropism for ciliated cells of the respiratory tract [20,21]. By attaching to the cilia and apical border of the epithelium, they might evade the mucociliary clearance as a first defense mechanism.…”

“…Studies with respiratory viruses, such as influenza virus, human respiratory syncytial virus, and human metapneumovirus (HMPV), demonstrated upregulations of IFNα and IFNλ in vivo and in vitro [32,38]. The results of AMPV infection studies depended on whether they were conducted in vivo or in vitro [21,39]. They found a downregulation of IFNα in vivo and upregulations of total interferon titer as well as an upregulation of nitric oxide (NO) production in vitro.…”

Bioactive Compounds from Marine Sponges: Fundamentals and Applications

“…aMPV is a non-segmented single-stranded RNA virus from the family Paramoxyviridae [ 172 ]. The virus is highly virulent to avian species such as chickens and turkeys and causes a huge loss to the poultry industry [ 173 ]. The virus causes rhinotracheitis among turkeys and causes swollen head syndrome among chickens [ 173 ].…”

“…The virus is highly virulent to avian species such as chickens and turkeys and causes a huge loss to the poultry industry [ 173 ]. The virus causes rhinotracheitis among turkeys and causes swollen head syndrome among chickens [ 173 ]. The illness rate caused by aMPV among chicken flocks ranges between 30–80%, with a mortality rate among these chickens of approximately 15% [ 172 ].…”

Serological and Molecular Characterization of Avian Metapneumovirus in Chickens in Northern Vietnam

“…The detection rates of aMPV in northern Vietnam (17.2%) demonstrated a similar low prevalence to other countries. Three main possibilities for the low aMPV detection rates were: (i) aMPV poorly replicated in the respiratory tract of chickens compared to turkeys [45,46], (ii) relatively short viral shedding time (within one week post-infection) [25,26], and (iii) low level of viral shedding (the highest was about 10 2.7 TCID 50 /mL) [25]. Additionally, the sensitivity of the RT-PCR assay was known to affect the virus-detection results.…”