貂、狐、貉源犬瘟热病毒的分离鉴定与序列分析（英文）

采用能稳定表达犬信号淋巴细胞活性分子（SLAM）的Vero-DST细胞从发病貉、狐狸和水貂病料,分离获得5株病毒,经电镜形态观察、RT-PCR检测、理化特性测定和人工感染发病试验鉴定,均为犬瘟热病毒（CDV）,分别命名为HT-P（貉源）、THD1（貉源）、HD（貂源）、LN（貂源）和HB（狐源）。5个分离毒株TCID50为10-5.2～-7.3/ml;除鸡、鹅红细胞呈微弱阳性外,其余均未见血凝作用;对乳鼠的LD50分别为2×10-3.8～-4.8/ml,对实验兔无致病性,对貉有明显致病性作用。5株CDV H和N基因序列分析结果为5个分离株之间H基因nt序列同源性均达到97.5%以上,HT-P（貉源,山东青岛）与THD1（貉源,山东潍坊）的aa同源性为100%,二者与其他分离株间aa序列同源性为87.9%～99.1%;与chn等疫苗株基因nt序列和推导aa序列同源性普遍较低,分别为90.5～91.8和89.%～91.8%。5个分离株之间N基因nt序列同源性均≥94.5%,HT-P与THD1同源性最高（99.8%）,分离株之间aa序列除HT-P、THD1与HD（貂源,山东青岛）同源性较高（99.0%以上）外,其他．分离株之间同源性低。与chn等疫苗株nt序列同源性较低（90．9～93．5％）。此外，HD和LN（貂源，辽宁大连）发病区域相距较远，但具有较高的同源性，但与HB（狐源，河北沦州）具有相对较低的nt同源性，提示野毒株在易感动物上可能存在种属差异。分离毒株与疫苗株之间H和N蛋白基因差异，可能与CD免疫失败有关。

IDENTIFICATION AND ANALYSIS OF CANINE DISTEMPER VIRUS ORIGINATING FROM RACCOON DOG,FOX,OR MINK

It remains unclear why canine distemper virus（CDV） epidemics occur frequently in fox,mink,and Raccoon Dog populations despite of vaccination.We characterized 5 CDV-positive strains from tissue samples of ill Raccoon Dogs（HT-P and THD1）,foxes（HB）,and minks（HD and LN）.All 5 isolates showed cytopathic effects in Vero-DST cells and the tissue culture infective dosage range from 10-5.2 to 10-7.3 per ml.The median lethal dosage of the isolates in suckling mice ranged from 2 × 10-3.8 to 10-4.8 per ml,and each isolate was highly pathogenic in Raccoon Dogs but not in experimental rabbits. The CDV isolate hemagluttin （H） and nucleocapsid （N） gene nucleotide and deduced amino acid sequences were compared with those of other CDV strain sequences in GenBank. We found that the N gene nucleotide sequences between HD and LD were highly homologous despite of distant geographical origins. However, the N gene of HD had a relatively low nucleotide homology to HB, suggesting the differences of species in field isolates. Furthermore, our results revealed a significant difference in the immunogenicities of the H and N proteins in the vaccine strains, which might be the key reason for CDV vaccine failure.