Experimental study on co-infection of H9N2 avian influenza virus with Ornithobacterium rhinotracheale in specific- pathogen- free chickens

Subject Areas : Journal of Comparative Pathobiology

آیدین عزیزپور ¹ , حسین گودرزی ² , سعید چرخکار ³ , رضا ممیز ⁴ , محمدحسن حبل الورید ⁵

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Received: 2012-10-09 Accepted : 2012-12-04 Published : 2013-02-19

Keywords: H9N2 Influenza Virus, Ornithobacterium Rhinotracheal, Co-Infection, Tissue&#x0D, &#x0D, Tropism, SPF chickens,

Abstract :

In this study, pathogenesis of co-infection of (A/Chicken/Iran/ m.1/2010) H9N2 virus and (ORT-R87-7/1387) Ornithobacterium rhinotracheale bacteria, and tissue tropism and dissemination ofthis co-infection throughout the body of SPF chickens were investigated. The clinical signs andgross lesions of the infected chicks were also monitored. Forty, 21-day-old SPF chicks weredivided randomly into two groups (20 chicks in the experimental and 20 chicks in the controlgroup). At the age of three weeks, the chicks in the experimental group were inoculated by eyedropwith the virus of 106 EID50 and intratracheally with the bacteria of 1 ×١٠١٠CFU. Thesamples from various tissues were collected at 2, 4,6,8,10,12 and 14 days post-inoculation(DPI). We used culture on blood agar for detection of the bacteria and isolation assay inembryonated chicken eggs (SPF) to evaluate virus dissemination. Experimental group chickensexhibited depression, reduced appetite, ruffled feathers, more severe respiratory signs and 15%mortality. The most remarkable clinical signs appeared on day 3 PI. H9N2 was detected in thelungs and trachea on days 2 and 4 PI. The virus was also found in the Bursa of fabricius on days2 and 6 PI. The H9N2 virus was observed only on day 2 PI in Thymus and Liver, and only onday 8 PI in Kidneys. We could not trace the virus in the spleen, cecal tonsils and cloaca duringstudy. ORT was isolated in the swabs of trachea on days 2 and 4 PI. The bacteria was alsofound in the lungs on day 4 PI.But ORT was not detected in swab samples taken from heart andliver during study. The Results of this study indicated that H9N2 virus and ORT bacteria wasnot detected from days 6 and 10 PI, respectively and also concurrent infectious with H9N2 virusand ORT bacteria could exacerbates clinical signs and gross lesions in infected chickens