Molecular characterization of Marek's disease virus genomes isolated from white-fronted geese

为研究马立克氏病病毒1型（MDV 1）的基因组特征，于2003-2005年从俄罗斯远东地区采集了200只北海道羽尾雁、63只豆鹅、15只加拿大鹅和50只白额鹅的羽毛和血液样品。2003-2005年，在北海道采集了147只白额鹅的样本。从这些样品中提取细胞总DNA，并进行meq基因特异性巢式PCR检测MDV 1基因组。在针尾鹅中未检测到MDV基因组，但25-30%的鹅样本呈meq基因阳性。结果表明，在未发现临床症状的野鹅群体中存在MDV 1，本实验对白额鹅MDV 1基因组进行了核苷酸序列分析，以评估MDV 1株的致病性。MDV 1株meq基因的核苷酸序列与已报道的MDV 1强毒株非常相似。另外，在来自白额鹅的MDV 1毒株中也发现了糖蛋白（g）L基因的缺失，这在强毒株MDV 1中已有报道。结果表明，白额鹅中分离到的MDV 1株具有较强的毒力。然而，鹅源MDV 1的gB基因的核苷酸序列与从北海道地区的鸡中分离的MDV 1的极强毒株的核苷酸序列略有不同，表明MDV 1在鸡和鹅之间的传播目前不是那么频繁。应该注意的是，一个MDV 1毒株的meq基因与从北海道地区鸡中分离的极强MDV 1毒株的meq基因非常相似，因此有必要对来自鹅种群的大量样本进行研究。

To characterize the genomes of Marek's disease virus serotype 1 (MDV 1) isolated from wild geese, feather tips and blood samples were collected from 200 pintails in Hokkaido, 63 bean geese (Anser fabalis), 15 canada geese (Branta canadensis), and 50 white-fronted geese (Anser Albifrons) in the fareast area of Russia during 2003-2005. Samples were also collected from 147 white-fronted geese at Hokkaido during 2003-2005. Total cellular DNAs were extracted from these samples, and the meq gene-specific nested PCR was performed to detect the MDV 1 genome. The MDV genome was not detected from pintails, but 25-30% of samples from thses geese were positive for the meq gene. These results showed that MDV 1 is present in wild goose populations though no clinical signs were observed in these geese.In the next experiment, nucleotide sequence analysis of the MDV1 genomes obtained from white-fronted geese was done to estimate the pathogenicities of the MDV1 strains. The nucleotide sequences of the meq genes of the MDV1 strains were very similar to those of very virulent MDV1 reported previously. In addition, a deletion in the glycoprotein (g) L gene, which was reported in the very virulent MDV1, was also found in the MDV1 strains from white-fronted geese. These results suggested that the MDV1 strains detected in white-fronted geese are very virulent. However, nucleotide sequence of the gB gene of goose-derived MDV1 was slightly different from that of very virulent MDV1 isolated from chickens in the Hokkaido area, showing that the MDV1 transmission between chickens and geese is not so frequent at the present time. It should be noted that the meq gene of one MDV1 strain was very similar to that of very virulent MDV1 isolated from chickens in the Hokkaido area, and it will be necessary to study larger numbers of samples from goose populations.