Coronado Liani, Liniger Matthias, Muñoz-González Sara, Postel Alexander, Pérez Lester Josue, Pérez-Simó Marta, Perera Carmen Laura, Frías-Lepoureau Maria Teresa, Rosell Rosa, Grundhoff Adam, Indenbirken Daniela, Alawi Malik, Fischer Nicole, Becher Paul, Ruggli Nicolas, Ganges Llilianne
Centro Nacional de Sanidad Agropecuaria (CENSA), La Habana, Cuba; IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
Institute of Virology and Immunology IVI, Mittelhäusern, Switzerland.
Vet Microbiol. 2017 Mar;201:103-112. doi: 10.1016/j.vetmic.2017.01.013. Epub 2017 Jan 17.
In this study, we compared the virulence in weaner pigs of the Pinar del Rio isolate and the virulent Margarita strain. The latter caused the Cuban classical swine fever (CSF) outbreak of 1993. Our results showed that the Pinar del Rio virus isolated during an endemic phase is clearly of low virulence. We analysed the complete nucleotide sequence of the Pinar del Rio virus isolated after persistence in newborn piglets, as well as the genome sequence of the inoculum. The consensus genome sequence of the Pinar del Rio virus remained completely unchanged after 28days of persistent infection in swine. More importantly, a unique poly-uridine tract was discovered in the 3'UTR of the Pinar del Rio virus, which was not found in the Margarita virus or any other known CSFV sequences. Based on RNA secondary structure prediction, the poly-uridine tract results in a long single-stranded intervening sequence (SS) between the stem-loops I and II of the 3'UTR, without major changes in the stem- loop structures when compared to the Margarita virus. The possible implications of this novel insertion on persistence and attenuation remain to be investigated. In addition, comparison of the amino acid sequence of the viral proteins E, E1, E2 and p7 of the Margarita and Pinar del Rio viruses showed that all non-conservative amino acid substitutions acquired by the Pinar del Rio isolate clustered in E2, with two of them being located within the B/C domain. Immunisation and cross-neutralisation experiments in pigs and rabbits suggest differences between these two viruses, which may be attributable to the amino acid differences observed in E2. Altogether, these data provide fresh insights into viral molecular features which might be associated with the attenuation and adaptation of CSFV for persistence in the field.
在本研究中，我们比较了比那尔德里奥分离株和强毒株玛格丽塔毒株对断奶仔猪的毒力。后者引发了1993年古巴的经典猪瘟（CSF）疫情。我们的结果表明，在地方流行阶段分离出的比那尔德里奥病毒毒力明显较低。我们分析了在新生仔猪体内持续存在后分离出的比那尔德里奥病毒的完整核苷酸序列，以及接种物的基因组序列。比那尔德里奥病毒的共有基因组序列在猪体内持续感染28天后完全未变。更重要的是，在比那尔德里奥病毒的3'UTR中发现了一个独特的聚尿苷序列，在玛格丽塔病毒或任何其他已知的猪瘟病毒序列中均未发现。基于RNA二级结构预测，该聚尿苷序列在3'UTR的茎环I和II之间形成了一个长的单链间隔序列（SS），与玛格丽塔病毒相比，茎环结构没有重大变化。这种新插入序列对持续性和毒力减弱的潜在影响仍有待研究。此外，对比玛格丽塔病毒和比那尔德里奥病毒的病毒蛋白E、E1、E2和p7的氨基酸序列发现，比那尔德里奥分离株获得的所有非保守氨基酸替换都集中在E2中，其中两个位于B/C结构域内。在猪和兔身上进行的免疫和交叉中和实验表明这两种病毒存在差异，这可能归因于在E2中观察到的氨基酸差异。总之，这些数据为可能与猪瘟病毒在野外持续性的毒力减弱和适应性相关的病毒分子特征提供了新的见解。
