Niqueux Eric, Guionie Olivier, Schmitz Audrey, Hars Jean, Jestin Véronique
AAFSSA (French Agency for Food Safety), Research Laboratory on Poultry, Swine and Fish, Poultry and Rabbit Virology, Immunology, and Parasitology Unit, National Reference Laboratory for Avian Influenza and Newcastle Disease, B.P. 53, 22440 Ploufragan, France.
Avian Dis. 2010 Mar;54(1 Suppl):502-8. doi: 10.1637/8804-040109-ResNote.1.
Highly pathogenic (HP) avian influenza A viruses (AIVs) subtype H5N1 (subclade 2.2) were detected in wild birds during outbreaks in France during winter 2006 and summer 2007 in la Dombes wetlands (eastern France) and in Moselle wetlands (northeastern France), respectively. Blood samples from apparently healthy wild birds were collected in 2006 and 2007 from the end of the outbreak to several weeks after the influenza A outbreak inside and outside the contaminated areas, and in 2008 outside the contaminated areas. The samples were tested for the presence and/or quantitation of serum antibodies to influenza A subtypes H5 and N1 using hemagglutination inhibition tests (HITs), a commercial N1-specific enzyme-linked immunosorbent assay kit, and virus neutralization assay. In the HIT, low pathogenicity (LP) and HP H5 AIVs (belonging to H5N1, H5N2, and H5N3 subtypes) were used as antigens. One hundred mute swans were bled in the la Dombes outbreak area in 2006. During 2007, 46 mallards, 69 common pochards, and 59 mute swans were sampled in the Moselle outbreak area. For comparison, blood samples were also collected in 2007 from 60 mute swans from the Marne department where no HP H5N1 influenza A cases have been reported, and in 2008 from 111 sacred ibises in western France where no HP H5N1 influenza A infections in wild birds have been reported either. Mute swans (irrespective of their origin and time of sampling) and sacred ibises (from an area with no known outbreaks) had the highest prevalence of positive sera in the H5 HIT (49-69% and 64%, respectively). The prevalence of anti-H5 antibodies in mallards and common pochards was lower (28% and 27%, respectively). Positive H5- and N1-antibody responses were also significantly associated in swans (irrespective of their origin and time of sampling) and in sacred ibises. However, in swans from the area without outbreaks, the HIT titer against an H5N1 LPAIV was significantly higher than against an H5N1 2.2.1 HPAIV, whereas no difference could be shown for swans from the outbreak areas sampled in 2006 and 2007. These results suggest that ibises and swans from areas without declared outbreaks had acquired humoral immunity after AIV infections with subtypes H5 and N1 but independently from HP H5N1 infection. However, for swans living in outbreak areas, it cannot be excluded that this immunity might result from either a subclinical or a nonlethal infection by HP H5N1.
2006年冬季和2007年夏季，法国分别在东部的拉东布湿地和东北部的摩泽尔湿地爆发疫情期间，在野生鸟类中检测到高致病性（HP）甲型禽流感病毒（AIV）H5N1亚型（进化分支2.2）。2006年和2007年，在疫情结束后至甲型流感疫情爆发后的数周内，分别在污染区域内外以及2008年在污染区域外采集了看似健康的野生鸟类的血液样本。使用血凝抑制试验（HIT）、商用N1特异性酶联免疫吸附测定试剂盒和病毒中和试验检测样本中甲型流感H5和N1亚型血清抗体的存在情况和/或定量。在HIT中，使用低致病性（LP）和HP H5 AIV（属于H5N1、H5N2和H5N3亚型）作为抗原。2006年在拉东布疫情爆发地区对100只疣鼻天鹅进行了采血。2007年，在摩泽尔疫情爆发地区对46只绿头鸭、69只凤头潜鸭和59只疣鼻天鹅进行了采样。作为对照，2007年还从马恩省未报告HP H5N1甲型流感病例的60只疣鼻天鹅中采集了血液样本，2008年从法国西部未报告野生鸟类感染HP H5N1甲型流感的111只圣鹮中采集了血液样本。疣鼻天鹅（无论其来源和采样时间）和圣鹮（来自无已知疫情的地区）在H5 HIT中阳性血清的患病率最高（分别为49% - 69%和64%）。绿头鸭和凤头潜鸭中抗H5抗体的患病率较低（分别为28%和27%）。在天鹅（无论其来源和采样时间）和圣鹮中，H5和N1抗体阳性反应也显著相关。然而，在无疫情地区的天鹅中，针对H5N1低致病性禽流感病毒的HIT效价显著高于针对H5N1 2.2.1高致病性禽流感病毒的效价，而2006年和2007年在疫情爆发地区采样的天鹅中未显示出差异。这些结果表明，来自未宣布爆发疫情地区的鹮和天鹅在感染H5和N1亚型禽流感病毒后获得了体液免疫，但与HP H5N1感染无关。然而，对于生活在疫情爆发地区的天鹅，不能排除这种免疫可能是由HP H5N1的亚临床感染或非致死性感染导致的。
