Abstract: To understand the infectious status and molecular characteristics of Actinidia virus A（AcVA）and Actinidia virus B（AcVB）in kiwifruit（Actinidia sp.）grown in China，151 plants of kiwifruit were tested for the presence of the two viruses by Reverse transcription PCR（RT-PCR）. Results revealed that the average infection frequencies of AcVA and AcVB in kiwifruit samples were 15.2% and 17.9%，respectively. All six Actinidia species tested were positive to one or two viruses. Sequence analyzes of amplified fragments from ORF，ORF4 and ORF5 of AcVA genome showed that the virus isolates were molecularly divergent and the 269 bp fragments of ORF1 from different isolates shared nucleotide similarities of 77.3%–99.3%. In phylogenetic trees based on nucleotide sequences of three fragments，allAcVA isolates separated into two or three clades. The ORF5 fragment of 20 AcVB isolates amplified using primer set AcVB5F/5R had a size of 342 bp or 338 bp. All those isolates shared nucleotide similarities of 81%–100% with each other and 83.9%–99.7% with the corresponding sequence of the New Zealand isolate TP7-93B，and clustered into three clades in the phylogenetic tree constructed basing on nucleotide sequences of the fragment.

Key words: Actinidia, Actinidia virus A, Actinidia virus B, RT-PCR, sequence analysis