Title: Experimental co-infection of poultry with avian influenza and newcastle disease virus Authors
|Ch, Rami -|
|Costa-Hurtado, Mar -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 18, 2013
Publication Date: July 7, 2013
Citation: Pantin Jackwood, M.J., Afonso, C.L., Miller, P.J., Spackman, E., Kapczynski, D.R., Shepherd, E.M., Smith, D.M., Cha, R., Costa-Hurtado, M., Suarez, D.L., Swayne, D.E. 2013. Experimental co-infection of poultry with avian influenza and Newcastle disease virus [abstract]. Centers for Excellence in Influenza Research and Surveillance Annual Meeting. p. 64. Technical Abstract: Avian influenza virus (AIV) and Newcastle disease virus (NDV) are two of the most important viruses affecting poultry worldwide. Co-infections of poultry with AIV and NDV are a problem from both the clinical point of view and the diagnosis of these viruses, but little is known on the interactions between these two viruses when infecting poultry. We conducted three experiments in which we infected chickens, turkeys and Pekin ducks with lentogenic, mesogenic or velogenic strains of NDV, and with low pathogenicity (LP) or high pathogenicity (HP) AIV, as relevant to specific ecosystems, by giving the viruses simultaneously or sequentially. Pathogenesis (clinical signs, lesions), presence of the viruses in tissues, duration and titer of virus shedding and seroconversion to both viruses were evaluated. No clinical signs were observed in chickens co-infected with a lentogenic NDV vaccine strain (LaSota) and a LPAIV (A/Tk/VA/SEP/67/02 H7N2) or chickens infected with the two viruses given separately. However, the pattern of virus shedding was different, with co-infected birds shedding less amount of virus at 2 and 3 days post inoculation (dpi), and shedding more virus in subsequent time points, than birds infected with the single viruses. All turkeys inoculated with the same LPAIV, co-infected or not, presented similar mild clinical signs. Like chickens, co-infected turkeys had altered patterns of virus shedding which was especially evident in the group that received the LPAIV followed by lentogenic NDV. In a second study, we found that previous infection of chickens with more virulent NDV viruses (mesogenic and velogenic strains)(Pigeon 84 and CA2002) interfered with replication of a HPAIV (A/Ck/Queretaro/14588-19/95 H5N2) in tissues when NDV was given 2 days earlier; however all birds died in less than 4 days. Interestingly, chickens were refractory to infection with the HPAIV if infected 3 days previously with the mesogenic NDV, indicating that timing of the second infection is important. Likewise, previous infection of domestic ducks with a velogenic NDV (APMV-1/duck/Vietnam long Bien/78/02) interfered with infection with a LPAIV (A/MI/OH/421/87 H7N8), and vice versa. The velogenic NDV also increased the mean death time of ducks infected 2 days later with a HPAIV (A/duck/VN/NCDV-672/11 H5N1). In conclusion, previous or simultaneous infection of NDV and AIV can affect the replication dynamics and the disease caused by these viruses in poultry. This virus interference will depend on the virulence of the two viruses co-infecting the birds and the timing of the infections. The information obtained from these studies helps understand the possible interactions and outcomes of infection (disease and virus shedding) when AIV and NDV co-infect birds in the field.