Diagnosi sierologica e molecolare del virus della tristezza degli agrumi: esperienze pugliesi

Large sized foci of tristeza, a disease whose compulsory control is enforced in Italy, have recently been identified in citrus groves of the Ionian coast of Apulia (south-east Italy). Estimation of disease incidence is essential for tristeza management decision making. In view of the massive monitoring to be carried out for assessing the sanitary status of the groves in the area of the outbreaks, a virus-specific antiserum and a digoxigenin-labelled minus-sense riboprobe, complementary to the coat protein gene sequence, to be used for DAS-ELISA and dot-blot hybridisation tests, have been prepared. In ELISA, the antiserum recognized 21 of the 27 isolates from a collection of infected plants coming from seven different countries, whereas the totality of the isolates were identified by the riboprobe. When 16 citrus samples collected at random from one of the tristeza foci were analyzed, CTV was recognized molecularly and serologically in seven and two samples, respectively. The high sensitivity and reliability of molecular hybridisation make it a good alternative to serological methods for CTV detection.

In previsione delle estese indagini di campo per il rilevamento di CTV sono stati preparati specifici reagenti diagnostici di laboratorio. In particolare, sono stati prodotti un antisiero e una ribosonda marcata con digossigenina. In ELISA l'antisiero ha riconosciuto 21 dei 27 isolati di CTV presenti in collezione e provenienti da sette diversi Paesi, mentre in saggi di ibridazione a macchia la sonda ha reagito positivamente con tutti gli isolati saggiati. In una prova preliminare in cui sono stati analizzati 16 campioni prelevati a caso in uno dei focolai di "tristeza", CTV è stato identificato molecolarmente in sette campioni e sierologicamente solo in due.