Blueberry necrotic shock virus (BlShV) ELISA Kit

The rapid and random spread of blueberry shock ilarvirus (BlShV) in commercial plantings suggested that insects played a role in transmission. Transmission from infected field plants to trap plants only occurred during bloom, indicating that flowers were the avenue for infection and flower-visiting insects including pollinators were involved. Trap plants readily became infected during bloom when a honeybee hive was included in cages with diseased field plants and trap plants. There was limited transmission in cages without a hive and no transmission when healthy field bushes were caged with trap plants either with or without honeybees. Infective pollen survived within the hive for 1 but not 2 weeks. Western flower thrips did not transmit BlShV when they were allowed to feed on caged flowering trap plants in the presence of a source of infected pollen. Results of pollen washes, cell disruption, and electron microscopy show that particles of BlShV were on, in, and between the cells of the pollen tetrad. Pollen from infected plants germinated as readily as pollen from healthy plants. BlShV was seedborne, but at a low level. All 42 cultivars tested were susceptible to BlShV when inoculated by grafting. The primary mechanism of transmission appears to be the transfer of BlShV-contaminated pollen by honeybees from flowers on infected plants to flowers on healthy plants.

Blueberry shock virus (BlShV), an Ilarvirus sp. reported only on blueberry, was associated with scarring, disfigurement, and premature reddening of cranberry fruit. BlShV was detected by triple-antibody sandwich enzyme-linked immunosorbent assay and reverse-transcription polymerase chain reaction, and isometric virions of 25 to 28 nm were observed in cranberry sap. The virus was systemic, although unevenly distributed in plants. The coat protein of BlShV from cranberry shared 90% identity compared with BlShV accessions from blueberry on GenBank. Phylogenetic analysis of isolates of BlShV from cranberry collected from Wisconsin and Massachusetts did not indicate grouping by state. BlShV was detected in cranberry pollen, and seed transmission of up to 91% was observed. Artificial inoculation of cranberry flowers by pollination did not cause virus transmission. In some Nicotiana spp., rub inoculation of leaves with homogenized BlShV-positive cranberry flowers resulted in systemic infection. Cranberry plants recovered from symptoms the year after berry scarring occurred but continued to test positive for BlShV. The virus caused significant reduction in the average number of marketable fruit and average berry weight in symptomatic cranberry plants but recovered plants yielded comparably with healthy plants. Although recovery may limit the immediate economic consequences of BlShV, long-term implications of single- or mixed-virus infection in cranberry is unknown.