McKeown N E, Fenaux M, Halbur P G, Meng X J
Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, 1410 Price's Fork Road, Blacksburg, VA 24061-0342, USA.
Vet Microbiol. 2004 Nov 30;104(1-2):113-7. doi: 10.1016/j.vetmic.2004.08.013.
Human TT virus (TTV), originally isolated from a patient with post-transfusion hepatitis in 1997, is ubiquitous and non-pathogenic. Viruses related to human TTV have since been identified in non-human primates, bovine, ovine, porcine, feline, and canine. The objective of this study was to genetically characterize porcine TTV from pigs in different geographic regions. PCR primers based on the non-coding region of the only available porcine TTV isolate were designed to amplify porcine TTV DNA from sera of pigs in six different countries. Porcine TTV DNA was detected in 66.2% (102/154) of the swine sera. The percentages of positive pigs varied greatly from country to country and even within the same country: 33% in Iowa, USA; 40% in Thailand; 46% in Ontario, Canada; 80% in China; 85% in Korea; 90% in Spain; 100% in Quebec and Saskatchewan, Canada. A total of 40 porcine TTV isolates (five from each geographic region) were sequenced for a 218 bp fragment within the non-coding region. Sequence analyses revealed that porcine TTV isolates from different geographic regions shared 86-100% nucleotide sequence identity to each other. The prototype Japanese isolate of porcine TTV, Sd-TTV31, shared 90-97% nucleotide sequence identity with porcine TTV isolates reported in this study. Phylogenetic analysis showed that the clustering of the porcine TTV isolates is not associated with geographic origins. Although porcine TTV is not known to be associated with any swine disease, co-infection of pigs with TTV and other known swine pathogens may result in enhanced disease. There are also concerns for risk of potential human infection during xenotransplantation.
人细小病毒TTV于1997年最初从一名输血后肝炎患者体内分离出来，普遍存在且无致病性。此后，在非人类灵长类动物、牛、羊、猪、猫和犬中发现了与人类TTV相关的病毒。本研究的目的是对来自不同地理区域猪的猪细小病毒TTV进行基因特征分析。基于唯一可用的猪细小病毒TTV分离株的非编码区设计了PCR引物，以扩增来自六个不同国家猪血清中的猪细小病毒TTV DNA。在66.2%（102/154）的猪血清中检测到猪细小病毒TTV DNA。阳性猪的百分比在不同国家之间甚至在同一个国家内差异很大：美国爱荷华州为33%；泰国为40%；加拿大安大略省为46%；中国为80%；韩国为85%；西班牙为90%；加拿大魁北克省和萨斯喀彻温省为100%。对40株猪细小病毒TTV分离株（每个地理区域5株）的非编码区内218 bp片段进行了测序。序列分析表明，来自不同地理区域的猪细小病毒TTV分离株彼此之间的核苷酸序列同一性为86%-100%。猪细小病毒TTV的日本原型分离株Sd-TTV31与本研究报道的猪细小病毒TTV分离株的核苷酸序列同一性为90%-97%。系统发育分析表明，猪细小病毒TTV分离株的聚类与地理起源无关。虽然猪细小病毒TTV与任何猪病无关，但猪感染TTV与其他已知猪病原体的共同感染可能会导致疾病加重。人们还担心在异种移植过程中存在潜在人类感染的风险。
