Cagle Caran, Wasilenko Jamie, Adams Sean C, Cardona Carol J, To Thanh Long, Nguyen Tung, Spackman Erica, Suarez David L, Smith Diane, Shepherd Eric, Roth Jason, Pantin-Jackwood Mary J
Exotic and Emerging Avian Viral Diseases Unit, Southeast Poultry Research Laboratory, U.S. Department of Agriculture, 934 College Station Road, Athens, GA 30605, USA.
Avian Dis. 2012 Sep;56(3):479-87. doi: 10.1637/10030-120511-Reg.1.
In a previous study, we found clear differences in pathogenicity and response to vaccination against H5N1 highly pathogenic avian influenza (HPAI; HA dade 2.3.4) between Pekin (Anas platyrhynchos var. domestica) and Muscovy (Cairina moschata) ducks vaccinated using a commercial inactivated vaccine (Re-1). The objective of the present study was to further investigate the pathogenicity of H5N1 HPAI viruses in different species of ducks by examining clinical signs and innate immune responses to infection with a different strain of H5N1 HPAI virus (HA clade 1) in two domestic ducks, Pekin and Muscovy, and one wild-type duck, mallard (Anas platyrhynchos). Protection conferred by vaccination using the Re-1 vaccine against infection with this virus was also compared between Pekin and Muscovy ducks. Differences in pathogenicity were observed among the virus-infected ducks, as the Muscovy ducks died 2 days earlier than did the Pekin and mallard ducks, and they presented more-severe neurologic signs. Conversely, the Pekin and mallard ducks had significantly higher body temperatures at 2 days postinfection (dpi) than did the Muscovy ducks, indicating possible differences in innate immune responses. However, similar expression of innate immune-related genes was found in the spleens of virus-infected ducks at this time point. In all three duck species, there was up-regulation of IFN-alpha, IFN-gamma, IL-6, CCL19, RIG-I, and MHC class I and down-regulation of MHC class II, but variable expression of IL-18 and TLR7. As in our previous study, vaccinated Muscovy ducks showed less protection against virus infection than did Pekin ducks, as evidenced by the higher mortality and higher number of Muscovy ducks shedding virus when compared to Pekin ducks. In conclusion, infection with an H5N1 HPAI virus produced a systemic infection with high mortality in all three duck species; however, the disease was more severe in Muscovy ducks, which also had a poor response to vaccination. The differences in response to virus infection could not be explained by differences in the innate immune responses between the different types of ducks when examined at 2 days dpi, and earlier time points need to be evaluated.
在之前的一项研究中，我们发现，使用市售灭活疫苗（Re-1）接种疫苗后，北京鸭（Anas platyrhynchos var. domestica）和番鸭（Cairina moschata）对H5N1高致病性禽流感（HPAI；HA谱系2.3.4）的致病性和疫苗接种反应存在明显差异。本研究的目的是，通过检查两种家鸭（北京鸭和番鸭）以及一种野生型鸭（绿头鸭，Anas platyrhynchos）感染不同毒株的H5N1 HPAI病毒（HA分支1）后的临床症状和先天免疫反应，进一步研究H5N1 HPAI病毒在不同鸭种中的致病性。还比较了使用Re-1疫苗接种对北京鸭和番鸭感染该病毒的保护作用。在感染病毒的鸭中观察到致病性差异，因为番鸭比北京鸭和绿头鸭早2天死亡，并且表现出更严重的神经症状。相反，北京鸭和绿头鸭在感染后2天（dpi）的体温显著高于番鸭，表明先天免疫反应可能存在差异。然而，在这个时间点，在感染病毒的鸭脾脏中发现了相似的先天免疫相关基因表达。在所有三种鸭种中，IFN-α、IFN-γ、IL-6、CCL19、RIG-I和MHC I类基因上调，MHC II类基因下调，但IL-18和TLR7表达可变。与我们之前的研究一样，接种疫苗的番鸭对病毒感染的保护作用不如北京鸭，与北京鸭相比，番鸭的死亡率更高，排毒的番鸭数量更多，证明了这一点。总之，感染H5N1 HPAI病毒在所有三种鸭种中都导致了高死亡率的全身感染；然而，番鸭的病情更严重，对疫苗接种的反应也较差。在感染后2天检查时，不同类型鸭之间先天免疫反应的差异无法解释对病毒感染反应的差异，需要评估更早的时间点。
