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Natural Infection of Verbena and Phlox by a Recently Described Member of the Carmovirus Genus

A novel carmovirus infecting angelonia (Angelonia angustifolia) was recently described independently by researchers in the United States, Israel, and Germany (1,2,4). Angelonia flower break virus (AnFBV) and Angelonia flower mottle virus were proposed as appropriate names for this carmovirus. The virus, causing stunting, mild leaf mottle, flower mottling, and flower breaking symptoms has been detected in naturally infected angelonia in the United States, Israel, and Germany (2,4). Here we report the first detection of natural infection of verbena (in the United States and Israel) and phlox (in the United States) by using a recently developed double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA; Agdia, Elkhart, IN). Prior to this report, verbena was considered insusceptible to carmovirus infection (3) and phlox was known as an experimental host for AnFBV (2). A comparative serological study including 27 virus species, demonstrated that DAS-ELISA did not cross-react with any viruses that commonly infect ornamentals or are related to carmoviruses, showing that the polyclonal antibodies are specific to AnFBV. Antibody specificity was confirmed by the carmovirus group PCR test (Agdia). Furthermore, reverse transcription-polymerase chain reaction with AnFBV specific primers (2) produced the expected 1172-bp band from all ELISA-positive samples tested. Between November 2005 and March 2006, AnFBV was detected in 181 of 567 verbena, 26 of 143 phlox, and 193 of 267 angelonia samples submitted to Agdia Testing Services by commercial ornamental propagators for virus testing. Most samples were asymptomatic, although a few exhibited mild leaf mottle. It should be noted that the number of AnFBV-infected samples might not accurately reflect the actual number of commercially produced plants infected with AnFBV because most of the samples analyzed originated from virus elimination programs. The detection of natural AnFBV infection of verbena, phlox, and angelonia suggests that AnFBV may be more widespread in the ornamental industry than previously thought.

References: (1) S. Adkins et al. Phytopathology (Abstr.) 95(suppl.):S2, 2005. (2) S. Adkins et al. Phytopathology 96:460, 2006. (3) G. P. Martelli and M. Russo. Online publication. ICTVdB-The Universal Virus Database. 00.074.0.02, 2004. (4) S. Winter et al. New Disease Reports. Vol 12. Brit. Soc. Plant Pathol. Online publication, 2005.