Effect of infectious bronchitis virus on the infectivity and transmissibility of H5N2 low pathogenicity avian influenza virus in chickens

Authors: Pantin Jackwood, Mary; Smith, Diane; LEYSON, CHRISTINA - Orise Fellow; YOUK, SUNG-SU - Orise Fellow; JACKWOOD, MARK - University Of Georgia

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Low pathogenicity avian influenza virus (LPAIV) can produce a mild to moderate upper respiratory disease in chickens that can be aggravated by other factors including other respiratory pathogens. In this study we examined the effect of infection with infectious bronchitis virus (IBV) on the infectivity and transmissibility of a LPAIV in chickens. To determine the mean fifty percent bird infectious dose (BID50), specific pathogen free leghorn chickens were inoculated intranasally with 102, 104, or 106 mean egg infectious doses (EID50) of a H5N2 LPAIV (Mexico lineage), and 3 contact birds were added to each group to study transmissibility. One set of groups only received the LPAIV. A second set of groups were intranasally inoculated with an IBV virulent field strain (Ark) three days earlier. A third set of groups were inoculated simultaneously with IBV and LPAIV. Mild conjunctivitis was the only clinical sign observed in LPAIV-inoculated birds. Moderate to severe conjunctivitis was present in all birds inoculated with IBV, single or co-infected. The BID50 of the LPAIV was the same (<102 BID50) regardless if the birds were co-infected with IBV or not, and the virus transmitted to all contacts. However, co-infected birds from the groups that received the 102 EID50 dose of the LPAIV shed lower titers of LPAIV by the oropharyngeal route at 2 and 4 days post inoculation, indicating that IBV interfered with LPAIV replication, but did not prevent LPAIV infection or transmission to the contact birds.