Coinfection of avian influenza virus (H9N2 subtype) with infectious bronchitis live vaccine

Abstract

Avian influenza virus of H9N2 subtype is pathotyped as a non-highly pathogenic virus. However, frequent incidences of avian influenza of high mortality that are caused by H9N2 viruses have been observed in broiler chicken farms in Iran and some other Asian countries. Coinfections or environmental factors may be involved in such cases. Infectious microorganisms have been implicating in taking part in the cases of coinfection. We studied the effect of experimental coinfection of H9N2 avian influenza virus with infectious bronchitis live vaccine, which is used extensively in chicken farms in Iran. Clinical signs, gross lesions, viral shedding and mortality rate of the experimentally infected birds were examined. Coinfection of infectious bronchitis live vaccine and H9N2 avian influenza virus led to an extension of the shedding period of H9N2 virus, increasing the severity of clinical signs and mortality rates, causing macroscopic lesions in the embryos.

Determination of Infective Dose of H9N2 Avian Influenza Virus in Different Routes: Aerosol, Intranasal, and Gastrointestinal

“…A previous study demonstrated that the result of infection was similar after ducks were inoculated with H5N1 AIV by three routes (intranasal, intracloacal, or intraocular) [23], but H9N2 AIV could cause more serious pathogenicity to chickens by trachea inoculation than by vein inoculation with the same dose [24]. However, most of the experiments used the intranasal inoculation route to study the characteristics of H9N2 AIV [2,9,10]. Many studies indicated that H9N2 AIV could infect poultry by aerosols and virus aerosols were detected from the air of animal houses, but the inhalation-infective process and aerosol-infective dose were still unclear [11,25,26].…”

“…H9N2 avian influenza virus (AIV) is a low pathogenic virus of the family Orthomyxoviridae, but it has caused high morbidity and mortality to poultry when coinfected with other pathogens [1,2]. Notably, cases of humans infected with H9N2 AIV have been reported in Hong Kong and mainland China since the late 1990s [3,4].…”

“…H9N2 AIV could transmit in poultry by aerosols, but most experiments used intranasal inoculation to study the pathogenicity of this virus [2,9,10,11]. It has been demonstrated that a low infective dose of human influenza virus was required for a viral aerosol to infect volunteers, and H9N2 AIV aerosols could infect mammals at certain concentrations [14,15].…”

Prevalence of AIV subtype H9 among poultry with respiratory signs in Iraq

“…Several outbreaks caused by the H9N2 virus have been recorded in wide geographical regions, causing serious disease problems in commercial poultry in Iran, Pakistan and Middle East countries in the last decade (Alexander, 2003;2007;Capua & Alexander, 2004;Perk, 2009), particularly, when poultry are co-infected with other respiratory pathogens such as infectious bronchitis virus (Haghighat et al, 2008).…”

An H9N2 Influenza Virus Vaccine Prepared from a Non-Pathogenic Isolate from a Migratory Duck Confers Protective Immunity in Mice against Challenge with an H9N2 Virus Isolated from a Girl in Hong Kong

“…The hemagglutinin (HA) genes of Eurasian H9N2 viruses have been phylogenetically divided into G1, Y280, and Korean sublineages [10]. H9N2 viruses do not substantially cause severe disease in poultry, but co-infection with bacteria such as Staphylococcus aureus, Haemophilus paragallinarum, or attenuated coronavirus vaccine exacerbates the disease [13,22]. H9N2 viruses were also isolated from domestic pigs in China [38] and Korea, and from humans with febrile respiratory illness in Hong Kong in 1998, 1999, 2003, 2008, and 2009 [4,5,23,31].…”