Blueberry scorch virus (BlScV) is a member of the genus Carlavirus and one of the most widespread pathogens of highbush blueberry (Vaccinium corymbosum L.). The virus was first reported in the United States and has been reported in several countries in Europe, including Italy, Germany, the Netherlands, and Poland. Symptoms of scorch disease in highbush blueberry include necrosis of flower blossoms and leaves, shoot blight, and chlorosis. Sometimes BlScV infection is symptomless or limited to single blossoms and shoots, but all highbush blueberry cultivars are susceptible to virus infection. Cranberry (V. macrocarpon L.) and wild black huckleberry (V. membranaceum L.) are known as natural and symptomless hosts of BlScV (1). In June 2012, during the research concerning the occurrence of BlScV in plants outside Vaccinium sp., 15 leaf samples from five elderberry bushes (Sambucus nigra L., family Adoxaceae) were randomly collected from the Lodzkie region in Central Poland and three were positive in double antibody sandwich (DAS)-ELISA using specific antiserum (Agdia Inc., Elkhart, IN). To confirm the presence of the virus, total nucleic acid was extracted from ELISA-positive elderberry samples according to established protocol (T. Malinowski. Proc. 4th Int. EFPP Symposium, 445, 1996) and used in one step reverse transcription PCR. Primers were developed against the published NJ-2, BC-1, and BC-2 sequences of BlScV (GenBank Accession Nos. NC_003499, AY941198, and AY941199, respectively). The forward primer, RDP_1 (5′-ATGGCACTCACATACAGAAGTCC-3′), and the reverse primer, RDP_2 (5′-TGCCTCTTCAATGCACGATGTTC-3′), were used to amplify a 420-bp fragment of the RNA-dependent RNA polymerase gene of the virus. Amplicons of expected size were obtained from three DAS-ELISA-positive samples, while no products were observed for the negative control (DAS-ELISA-negative elderberry tissues). Sequence of one selected PCR product revealed 100, 88, and 87% nucleotide sequence identity and 100, 96, and 96% amino acid sequence identity with BC-2, NJ-2, and BC-1, respectively. BlScV-infected elderberry bushes were asymptomatic. As BlScV is transmitted by aphids in a non-persistent manner, infected elderberry bushes near highbush blueberry plantings may play an important role in virus spread. The potential for BlScV infection of plants outside family Ericaceae should be investigated. To the best of our knowledge, this is the first report of BlScV infecting elderberry.
Reference: (1) R. R. Martin et al. Viruses 4:2831, 2012.