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Studies on the Lowly Pathogenic Avian Influenza Virus
Infections in Selected Avian Species
avian influenza virus,lowly pathogenic,pigeon,cyclophosphamide,immunosuppressive,Nested reverse transcriptase-polymerase chain reaction,
|Publication Year :||2005|
|Abstract:||本實驗探討鴿子在注射環磷醯胺(CY)後，是否會因免疫系統受到抑制而提升對家禽流行性感冒病毒 (AIV)之感受性。以低病原性的台灣AIV分離株 A/chicken/Taiwan/1209/03 (H5N2)及A/chicken/Taiwan/3152/03 (H6N1)經眼鼻路徑接種，並利用巢式反轉錄聚合酶連鎖反應(nested RT-PCR)和雞胚胎蛋病毒分離等2種方式進行偵測。在H5N2及H6N1的感染試驗中，施打與無施打CY的鴿子，於21天的觀察期內皆無排毒及抗體陽轉之情形，並且無法在氣管、肺、胰、脾、腎及直腸等臟器檢測到病毒。H6N1試驗中的同居感染雞隻也為相同的陰性結果。因此推論鴿子在免疫抑制的情形下，不但仍對這2株AIV具有抗性，也不會媒介病毒的傳播使其它鴿子或雞隻感染。在本實驗中也利用H5N2 AIV進行肉雞的接種試驗，以探討病毒在組織臟器的殘留情形。結果顯示在感染後的5和7天，以nested RT-PCR可在氣管和直腸偵測到病毒，心肌及肌胃則在第5天，腦和骨髓的出現情形較少，胸肌、翅肌或腿肌皆為陰性。另外，在2004年10月到2005年4月間，對台灣地區994隻鴨隻、71隻鴿子以及80隻寵物鳥進行AIV的調查，結果於2件鴨的檢體中分離到H1N1亞型AIV，鴨的分離率為0.19% (2/1049)，鴿子為0% (0/78)，寵物鳥為 0% (0/87)。由部分NP基因的序列推論，本次所分離到的毒株，與鳥源的H1N1亞型AIV較為接近，與豬或人源的H1N1則較為疏遠。|
Susceptibility to infection with avian influenza virus (AIV) was studied in healthy and immunodepressed pigeons, which were treated with the immunosuppressant cyclophosphamide (CY) before infection. Two subtypes of lowly pathogenic (LP) AIV (A/chicken/Taiwan/1209/03 H5N2 and A/chicken/Taiwan/3152/03 H6N1) were inoculated via oculonasal route. Nested reverse transcriptase-polymerase chain reaction (nested RT-PCR) and virus isolation were used as detective methods. The CY-treated and -untreated pigeons in both experiments did not shed viruses or become antibody positive throughout the 21-day observation period. All pigeons were negative for AIV RNA when trachea, lung, pancreas, spleen, kidney and rectum tissues were tested. The negative results were also obtained in noninoculated chickens which placed as contact controls in H6N1 AIV experiments. Therefore, it was concluded that the pigeons were resistant to infection with these LPAIV, and did not serve as a transmissible host, even in immune dysfunction. Following oculonasal inoculation with LPAIV (H5N2) in broiler chickens, virus was detected in trachea and rectum on 5 and 7 days postinoculation (DPI) by nested RT-PCR. AIV was also detected in myocardium and gizzard on 5 DPI, but rarely detected in brain and marrow on 5 or 7 DPI. No AI virus was prsent in breast, wing and thigh meat. The AI survey for 994 ducks, 71 pigeons and 80 pet birds in Taiwan was conducted from October 2004 to April 2005, we isolated two H1N1 AIVS from ducks. The isolation rates were 0.19% (2/1049), 0% (0/78) and 0% (0/87) in ducks, pigeons and pet birds, respectively. The partial NP genes of this two isolates were found to be closer to H1N1 avian viruses and to be different from H1N1 swine and human viruses.
|Appears in Collections:||獸醫學系|
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