Occurrence, Distribution, and Molecular Characterization of Citrus yellow vein clearing virus in China

In 2009, a new citrus viral disease caused by Citrus yellow vein clearing virus (CYVCV) was discovered in China. To more effectively monitor the presence of CYVCV, a survey was conducted in 166 citrus orchards from 11 major citrus-growing provinces in China from May 2014 to April 2016. In all, 458 of a total of 2,350 citrus samples tested positive for CYVCV, demonstrating that the virus is widely distributed in China. In this study, the complete genome sequences of 19 CYVCV isolates from different provinces and hosts were sequenced and characterized. Comparisons of the whole-genome sequences of these 19 CYVCV isolates as well as 4 isolates previously reported from around the world revealed that the sequence identity ranged from 97.1 to 99.8%, indicating that there is a very low level of sequence heterogeneity among CYVCV isolates of different geographic origins and hosts. Phylogenetic analysis of these 23 genomic sequences suggested that all of the isolates from China were clustered into the same clade, clearly apart from the CYVCV isolates from Turkey and Pakistan. To our knowledge, this is the first extensive survey conducted in China for CYVCV incidence.