Blois Sylvain, Mallus Francesca, Liciardi Manuele, Pilo Cristian, Camboni Tania, Macera Lisa, Maggi Fabrizio, Manzin Aldo
Department of Biomedical Sciences, Clinical Microbiology and Virology Unit, University of Cagliari Medical School, Cagliari, Italy.
Istituto Zooprofilattico Sperimentale Sardegna, Department of Cagliari, Cagliari, Italy.
PLoS One. 2014 Nov 20;9(11):e113720. doi: 10.1371/journal.pone.0113720. eCollection 2014.
Torque teno viruses (TTVs) are a large group of vertebrate-infecting small viruses with circular single-stranded DNA, classified in the Anelloviridae family. In swine, two genetically distinct species, Torque teno sus virus 1a (TTSuV1a) and 1b (TTSuV1b) are currently grouped into the genus Iotatorquevirus. More recently, a novel Torque teno sus virus species, named Torque teno sus virus k2b (TTSuVk2b), has been included with Torque teno sus virus k2a (TTSuVk2a) into the genus Kappatorquevirus. In the present study, TTSuV1 (TTSuV1a and TTSuV1b), TTSuVk2a and TTSuVk2b prevalence was evaluated in 721 serum samples of healthy pigs from Sardinian farms, insular Italy. This is the largest study to date on the presence of TTSuV in healthy pigs in Italy. The global prevalence of infection was 83.2% (600/721), being 62.3% (449/721), 60.6% (437/721), and 11.5% (83/721) the prevalence of TTSuV1, TTSuVk2a and TTSuVk2b, respectively. The rate of co-infection with two and/or three species was also calculated, and data show that co-infections were significantly more frequent than infections with single species, and that TTSuV1+TTSuVk2a double infection was the prevalent combination (35.4%). Quantitative results obtained using species-specific real time-qPCR evidenced the highest mean levels of viremia in the TTSuV1 subgroup, and the lowest in the TTSuVk2b subgroup. Interestingly, multiple infections with distinct TTSuV species seemed to significantly affect the DNA load and specifically, data highlighted that double infection with TTSuVk2a increased the viral titers of TTSuV1, likewise the co-infection with TTSuVk2b increased the titers of TTSuVk2a.
细小病毒（TTVs）是一大类感染脊椎动物的小型病毒，具有环状单链DNA，归类于圆环病毒科。在猪中，目前有两种基因不同的病毒，即猪细小病毒1a（TTSuV1a）和1b（TTSuV1b），被归入环曲病毒属。最近，一种新的猪细小病毒种，命名为猪细小病毒k2b（TTSuVk2b），已与猪细小病毒k2a（TTSuVk2a）一起被归入卡帕细小病毒属。在本研究中，对来自意大利撒丁岛农场的721份健康猪血清样本中TTSuV1（TTSuV1a和TTSuV1b）、TTSuVk2a和TTSuVk2b的流行情况进行了评估。这是迄今为止关于意大利健康猪中TTSuV存在情况的最大规模研究。总体感染率为83.2%（600/721），其中TTSuV1、TTSuVk2a和TTSuVk2b的感染率分别为62.3%（449/721）、60.6%（437/721）和11.5%（83/721）。还计算了两种和/或三种病毒共感染的比率，数据显示共感染比单一病毒感染更为常见，且TTSuV1+TTSuVk2a双重感染是最常见的组合（35.4%）。使用种特异性实时定量PCR获得的定量结果表明，TTSuV1亚组的病毒血症平均水平最高，而TTSuVk2b亚组的最低。有趣的是，不同TTSuV种的多重感染似乎显著影响DNA载量，具体而言，数据突出显示TTSuVk2a的双重感染增加了TTSuV1的病毒滴度，同样，TTSuVk2b的共感染增加了TTSuVk2a的滴度。
