Sección Genética Evolutiva, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay.
Vet Microbiol. 2012 Mar 23;155(2-4):214-9. doi: 10.1016/j.vetmic.2011.09.017. Epub 2011 Sep 29.
Canine parvovirus type 2 (CPV-2), which causes acute hemorrhagic enteritis in dogs, is comprised of three antigenic variants (2a, 2b, and 2c) that are distributed worldwide with different frequencies. Variant prevalence was analyzed in 150 CPV-2-positive samples collected from the Uruguayan dog population in 2007-2010. Samples were analyzed with polymerase chain reaction, restriction fragment length polymorphism, and sequencing of the coding region for the largest and most variable loop of the VP2 capsid protein. CPV-2c was the only strain detected from 2007 to 2009. Uruguayan CPV-2c showed high homogeneity in both nucleotide and amino acid sequences, indicating a low level of genetic variability. In 2010, an unexpected epidemiological change occurred in Uruguay as a consequence of the appearance of a novel CPV-2a strain. This variant rapidly spread through the Uruguayan dog population and was detected in 20 of the 52 cases (38%) analyzed in 2010. CPV-2a sequences were identical in all field viruses analyzed, and in addition to the characteristic 426Asn residue, the sequences showed amino acid substitutions (267Tyr, 324Ile, and 440Ala) not observed in the Uruguayan CPV-2c. These data and the first detection in April 2010 suggest that the CPV-2a variant recently emerged in Uruguay and underwent clonal expansion. This observation is the first case in which a CPV-2a variant increased its frequency in a dog population where CPV-2c was prevalent. Our results emphasize the dynamic changes in CPV variants and highlight the importance of ongoing surveillance programs to provide a better understanding of virus epidemiology.
犬细小病毒 2 型（CPV-2）可引起犬急性出血性肠炎，由三种抗原变异体（2a、2b 和 2c）组成，在全球范围内分布，频率不同。2007-2010 年，从乌拉圭犬群中采集了 150 份 CPV-2 阳性样本，分析了变异体的流行情况。通过聚合酶链反应、限制性片段长度多态性和 VP2 衣壳蛋白最大和最可变环的编码区测序分析了这些样本。2007 年至 2009 年，仅检测到 CPV-2c 株。乌拉圭 CPV-2c 在核苷酸和氨基酸序列上均具有高度同源性，表明遗传变异性较低。2010 年，由于一种新型 CPV-2a 株的出现，乌拉圭发生了意外的流行病学变化。这种变异株迅速在乌拉圭犬群中传播，并在 2010 年分析的 52 例病例中的 20 例（38%）中检测到。所有野外病毒分析的 CPV-2a 序列均相同，除了特征性的 426Asn 残基外，序列还显示了在乌拉圭 CPV-2c 中未观察到的氨基酸取代（267Tyr、324Ile 和 440Ala）。这些数据以及 2010 年 4 月首次检测到的结果表明，CPV-2a 变异株最近在乌拉圭出现，并经历了克隆扩张。这是首次在 CPV-2c 流行的犬群中，CPV-2a 变异株增加其频率的情况。我们的研究结果强调了 CPV 变异株的动态变化，并突出了持续监测计划的重要性，以更好地了解病毒的流行病学。
