Meister Tanja, Lussy Helga, Bakonyi Tamás, Sikutová Silvie, Rudolf Ivo, Vogl Wolfgang, Winkler Hans, Frey Hans, Hubálek Zdenek, Nowotny Norbert, Weissenböck Herbert
Institute of Pathology and Forensic Veterinary Medicine, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria.
Vet Microbiol. 2008 Mar 18;127(3-4):237-48. doi: 10.1016/j.vetmic.2007.08.023. Epub 2007 Aug 19.
Usutu virus (USUV), family Flaviviridae, has been responsible for avian mortality in Austria from 2001 to 2006. The proportion of USUV-positive individuals among the investigated dead birds decreased dramatically after 2004. To test the hypothesis that establishment of herd immunity might be responsible, serological examinations of susceptible wild birds were performed. Blood samples of 442 wild birds of 55 species were collected in 4 consecutive years (2003--2006). In addition, 86 individuals from a birds of prey rehabilitation centre were bled before, at the peak, and after the 2005 USUV transmission season in order to identify titre dynamics and seroconversions. The haemagglutination inhibition test was used for screening and the plaque reduction neutralization test for confirmation. While in the years 2003 and 2004 the proportion of seropositive wild birds was <10%, the percentage of seroreactors raised to >50% in 2005 and 2006. At the birds of prey centre, almost three quarters of the owls and raptors exhibited antibodies before the 2005 transmission season; this percentage dropped to less than half at the peak of USUV transmission and raised again to almost two thirds after the transmission season. These data show a from year to year continuously increasing proportion of seropositive wild birds. The owl and raptor data indicate significant viral exposure in the previous season(s), but also a number of new infections during the current season, despite the presence of antibodies in some of these birds. Herd immunity is a possible explanation for the significant decrease in USUV-associated bird mortalities in Austria during the recent years.
乌苏图病毒（USUV）属于黄病毒科，在2001年至2006年期间导致了奥地利的鸟类死亡。2004年之后，在被调查的死亡鸟类中，USUV阳性个体的比例急剧下降。为了验证群体免疫的建立可能是其原因这一假设，对易感野生鸟类进行了血清学检查。连续4年（2003 - 2006年）采集了55个物种的442只野生鸟类的血样。此外，在2005年USUV传播季节之前、高峰期和之后，对一家猛禽康复中心的86只个体进行了采血，以确定抗体滴度动态和血清转化情况。采用血凝抑制试验进行筛查，蚀斑减少中和试验进行确认。在2003年和2004年，野生鸟类血清阳性的比例<10%，而在2005年和2006年，血清反应阳性者的比例升至>50%。在猛禽中心，在2005年传播季节之前，近四分之三的猫头鹰和猛禽表现出抗体；这一比例在USUV传播高峰期降至不到一半，在传播季节之后又升至近三分之二。这些数据表明，血清阳性野生鸟类的比例逐年持续增加。猫头鹰和猛禽的数据表明，在前一个季节有大量病毒暴露，但尽管其中一些鸟类存在抗体，在当前季节仍有一些新感染发生。群体免疫可能是近年来奥地利与USUV相关的鸟类死亡显著减少的一个原因。
