Characterization of an Isolate of Tobacco Necrosis Virus From Zucchini

Tobacco necrosis virus (TNV) was isolated from glasshouse zucchini plants in Liguria, northern Italy, showing yellow spots on young leaves and necrotic symptoms on older leaves, petioles and stems. No other viruses were present in these plants. Experimentally, the virus systemically infected zucchini seedlings grown in naturally infected soil but only local infections were induced when leaves and roots were mechanically inoculated. The virus was identified as serotype D, devoid of satellite particles. This appears to be the first report of TNV in zucchini. Three ELISA procedures for field detection of TNV using polyclonal antibodies for serotype D were compared. Antibodies were conjugated with I) alkaline phosphatase (AP-AB);2) N-Hydroxy-succinimid obiotin (BNHS-Ab); 3) N-biotinyl-6-aminocaproic hydrazide (BACH-Ab). The procedure using BNHS-Ab detected the lowest concentration of the homologous virus, followed by BACH-Ab and AP-Ab. Only with biotinylated antibodies. TNV serotype A was also detected.