一个引起玉米矮花叶病的甘蔗花叶病毒基因组全序列测定及其结构分析

测定了从浙江省呈现矮花叶病症状的玉米上分离得到的一个马铃薯Y病毒属病毒RNA的核苷酸全序列.该病毒分离物的RNA基因组由9596个核苷酸组成（不包括polyA尾）.单一的ORF由9192个核苷酸组成,编码一个分子量为346.1ku的聚合蛋白.该蛋白结构特征与高粱花叶病毒（SrMV）中国甘蔗分离物和一个玉米矮花叶病毒（MDMV）保加利亚分离物基因组编码的蛋白非常相似.序列分析表明,该病毒分离物与甘蔗花叶病毒（SCMV）各分离物（已报道的仅为基因组3’末端序列）同源性最高,与SrMV和MDMV同源性次之,而与约翰逊草花叶病毒（JGMV）同源性最低.根据马铃薯Y病毒属区分不同病毒和株系的分类标准,报道的玉米病毒分离物应当鉴定为SCMV的一个株系.然而,该分离物在HC-Pro,P3和CI蛋白区域和SrMV中国甘蔗分离物具有极高的氨基酸同源性.

种禽场A亚群禽白血病病原学调查及分离株遗传进化分析

【目的】了解广东地区种禽场A亚群禽白血病病毒(ALV-A)流行情况.【方法】从A、B、C、D 4个种禽场采集1 561份血浆样品,接种DF-1细胞,培养7 d后通过ELISA方法对细胞上清液进行p27抗原检测,通过PCR、间接免疫荧光试验2种方法对p27抗原阳性样品进行鉴定.【结果和结论】从4个种禽场共检出71份阳性样品,外源性禽白血病病毒分离阳性率为4.6%.其中,仅从C种禽场分离到2株ALV-A,命名为GD13-1和GD13-2,前病毒全基因序列分别为7 721和7 715 bp,且GD13-2与J亚群禽白血病病毒混合感染.与国内外其他ALV-A的LTR、gp85核苷酸序列进行分析比对,发现该研究分离的2株ALV-A与国内A亚群分离株SDAU09E2相似度最高,其中与LTR相似性分别为96.9%、97.2%,与gp85相似性分别为98.4%、98.7%;与广东地区5年前ALV-A分离株GD08的LTR核苷酸序列相似性分别为88.9%、89.5%,与gp85相似性分别为98.5%、98.8%.调查结果表明,广东地区部分种禽场内仍然存在ALV-A感染,但ALV-A已经不是流行毒株,且变异程度不大.

Complete Genome Sequencing and Genetic Variation Analysis of Two H9N2 Subtype Avian Influenza Virus Strains

[Objective] The study aimed to investigate the genetic variation characters of entire sequences between two H9N2 subtype avian influenza virus strains and other reference strains.[Method] The entire sequences of 8 genes were obtained by using RT-PCR,and these sequences were analyzed with that of six H9N2 subtype avian influenza isolates in homology comparison and genetic evolution relation.[Result] The results showed that the nucleotide sequence of entire gene of the strain shared 91.1%-95.4% homology with other seven reference strains,and PG08 shared the highest homology 91.3% with C/BJ/1/94;ZD06 shared the highest homology 92.3% with D/HK/Y280/97.HA cleavage sites of two H9N2 subtype avian influenza virus isolated strains were PARSSR/GLF,typical of mildly pathogenic avian influenza virus.[Conclusion] Phylogenetic tree for entire gene of eight strains showed that the genetic relationship was the closest between ZD06 and C/Pak/2/99 strains,which belonged to the Eurasian lineage;PG08 shared the highest homology 91.3% with ZD06,it may be the product of gene rearrangements of other sub-lines.

PCR Detection and Sequence Analysis of Duck Circovirus in Sick Muscovy Ducks

The duck circovirus （DuCV） infection in sick ducks from Fujian Province was investigated. The liver samples of 43 sick Muscovy ducks with infectious serositis were collected from 12 duck farms in Fujian Province Based on the published sequences of DuCV, two primers were designed for the detection of DuCV and four pairs of primers were designed to amplify four overlapping fragments that cover the complete genome of DuCV. The specific PCR products were amplified from positive samples. The fragments were then cloned into pMD18-T vector and sequenced, and the full length genomic sequence of the FJ0601 isolate of DuCV was obtained. PCR analysis showed that the proportion of ducks which were positive for circovirus was 79% and 10 out of the 12 farms were positive. Sequence analysis showed that the complete genome of DuCV-FJ0601 was 1988 bp and possessed features common to the family Circoviridae which included a stem-loop structure and the Rep protein motifs. Homology analysis showed that FJ0601 isolate of DuCV had 97.3%-97.5% nucleotide sequence identity to all the four Taiwan isolates （TC1/2002, TC2/2002, TC3/2002, TC4/2002）, 82.9% identity to the America （33753-52） isolate and 82.3% identity to the Germany isolate. Phylogenetic analysis with Clustal W, however, showed that FJ0601 isolate of DuCV was on a common branch with Taiwan isolates, and Germany and America isolates belonged to the other branch.

The complete genomic sequence analysis of genotype 4 human astrovirus HASTVgz01 strain in Guangzhou

To analyze the genomic molecular structure and genotype of human astrovirus isolated from infant in Guangzhou of China, the primers were designed based on the genomic sequence of astrovirus from the C, enBank and the target sequence were amplified by RT-PCR. Then the PCR-products were cloned to T vector and sequenced. The genomic nucleotide sequences were analyzed by the programs CLUSTAL W and DNASTAR. It was found that the full genomic length of HASTVgz01 strain was 6721 bp and the ORFs were 6558 bp. The 5＇ and 3＇UTR were 82 and 81 nucleotides. The genome included 3 open reading frames （ORFs） ： ORFla, ORFlb and ORF2. The 5＇-terminal ORFla started at nueleotide 83 and extended to nucleotide 2845. ORFlb （nt 2785 to nt 4332） overlaped ORFla by 61 nueleotides. The 3＇-terminal ORF2 began at nucleotide 4325 and terminated at nucleotide 6640. ORF2 had 2316 nucleotides. Compared with other astrovirus sequences in GenBank, the homology of the amino acid sequence of ORF2 of HASTVgz01 strain with that of serotype 4 was 93%. Homology with other serotypes ranged from 61% to 70%. The complete nucleotide sequence of astrovirus HASTVgz01 strain isolated from Guangzhou in China was 6721 bp in length, GenBank accession NO. DQ344027. Comparing the ORF2 of astrovirus HASTVgz01 with the known sequences of types 1-8 the highest homology was serotype 4 （93%）. Comparative sequence analysis of the HASTVgz01 ORF2 with the reported human astrovirus sequences revealed that the isolated astrovirus belongs to genotype （serotype） 4.