Sequence Analysis Of RGDV From Three Different Regions And The Affinity With Vectors

Rice Gall Dwarf Virus(RGDV)is transmitted by Recila dosralis、Nephotettix cincticeps and Nephotettix apicalis, belonging to genus Phytoreovirus, family Reoviridae.The disease caused by rice gall dwarf virus is firstly found in Gaozhou, Guangdong province in China in 1976, then spreaded quickly. In 1981, the disease is founded in Zhanjiang area of Guangdong, and then outbroken in Beiliu of Guangxi province, in 1995 the disease happened in Yunfu, Guangdong. The disease took place in Xingning in 2001,the investigation in 2014-2015 in Heyuan, Meizhou, Shaoguan in Guandong and Sanya,Qiongzhou in Hainan also showed the occurance of rice gall dwarf virus disease. Thus, the occurrence of rice gall dwarfvirus disease is expanding in China, which is an important scientific and social problem to resolve. To reveal the mechanism of RGDV spreading, we carried researches as follows:Firstly, we investigated the occurace of rice gall dwarf disease and the species and quantity of vectors. Results shows that there are great differences in the degree of RGDD and species and quantity of vectors. The RGDD in Sanya is light, and the main vectors is Nephotettix virescens and Recila dosralis, the numbers of each vector is about 1-2 and 0-1.The RGDD in Luoding is serious, the main vectors is Nephotettix cincticeps and Recila dosralis and the number is 10-20 and 5-10. The RGDD in Xingning is serious, the main vector is Nephotettix cincticeps and Recila dosralis, while the number is 10-15 and 10-15.Secondly, we measured the virus acquisition rate of Recila dosralis and Nephotettix cincticeps from Luoding and Xingning to RGDV from three regions mentioned above. we compared affinity of different kinds of vectors to RGDV. Result showed that The affinity of three vectors to RGDV determined show that Recila dosralis is main transmitted vector,Nephotettix cincticepsis minor transmitted vector. The lowest affinity of RGDV vector is Nephotettix virescens.Thirdly, The leafhoppers no matter Recila dosralis and Nephotettix cincticeps shows high affinity to local RGDV, it is speculated that the virus may influenced and then generated mutations to promote virus spread.Fourthly, we sequenced the whole genome of RGDV from Luoding, Xingning and Sanya, analyzed the coding proteins of 12 segments of each RGDV isolates. The result shows that: the capsid protein P8 is completely identical for the important function while the minor capsid protein P2 have 5 main amino acid differences which may effect the affinity of vector to virus. The proteins of viroplasm formation is Pns7, Pns9 and Pns12 respectively have differences in the three isolates may affect the affinity.In this study, comparing the difference of affinity and amino acid sequences, we inferred that the difference of affinity may effected by genetic difference, which may promote the virus spreading.