Identification of an Isolate of Potato virus Y-Tuber Necrotic Strain on Clary Sage (Salvia sclarea).

In 1999, clary sage plants (Salvia sclarea L.) at the Herb Garden of Casola Valsenio (Emilia-Romagna Region, northern Italy) exhibited malformed leaves with yellow spots and line patterns. Sap from leaves of symptomatic sage plants caused symptoms in inoculated Chenopodium amaranticolor Coste et Reyn. plants (local chloro-necrotic lesions developed 7 to 10 days after inoculation) and Nicotiana tabacum L. 'White Burley' and 'Samsun' plants (systemic veinal necrosis developed ≈ 2 weeks after inoculation). Leaves from symptomatic sage plants tested positive for Potato virus Y (PVY) based on immunoelectron microscopy, gold-labeled decoration, and protein A sandwich enzyme-linked immunosorbent assay (ELISA), using antiserum to PVY (PVAS 50a, American Type Culture Collection, Manassas, VA). Double-antibody sandwich-ELISA, using specific monoclonal antibodies (BioReba AG, Reinach, Switzerland) to the tobacco veinal necrosis strain group of PVY (PVY-N), revealed that the PVY isolate from sage belonged to this group. Immunocapture-reverse transcription-polymerase chain reaction, using specific primers for PVY and the tuber necrotic strain of PVY (PVY-NTN), further classified the sage isolate as PVY-NTN (1). PVY-NTN causes serious damage to potato in Europe. Clary sage, one of the most important aromatic plants cultivated worldwide as a source of essential oils, represents a new natural host of PVY-NTN. Reference: (1) H. L. Weidemann and E. Maiss. J. Plant Dis. Prot. 103:337, 1996.

Occurrence of Potato Tuber Necrotic Ringspot Disease (PTNRD) in Italy.

Potato tuber necrotic ringspot disease, caused by a tuber necrotic isolate of potato virus YN named PVYNTN, was originally described in Hungary in 1980; later on, the disease spread throughout northern and eastern Europe (1). Recently, the virus was reported in Portugal (2) on fresh-market potatoes. During the summer of 1997, the disease appeared in the north of Italy, causing serious damage in processing and fresh-market potatoes. After harvesting, we observed in most of the potato cultivars tubers showing the typical superficial necrotic rings and areas. These viral lesions were predisposed to secondary infection by fungi and bacteria. Moreover, PVYNTN causes degradation of tuber starch into simple carbohydrates. This metabolic activity resulted in undesirable browning in chips. In different areas of northern Italy, samples were collected from 48 stocks of cv. Hermes, the most important processing cultivar in Italy, and from 12 stocks of other potato cultivars (Ernterstolz, Liseta, Monalisa, Primura, Kennebec). The original seed of the stocks came from five different European countries: Austria, Italy, Scotland, Switzerland, and The Netherlands. Samples were serologically tested by indirect enzyme-linked immunosorbent assay with specific monoclonal antibodies to tobacco venial necrosis strain group of PVY. The results showed that 37 out of 60 analyzed stocks were infected by an isolate belonging to PVYN group, 7 stocks were infected by a common isolate of PVY, and 16 were PVY free. To distinguish the tuber-necrosis isolate (PVYNTN) from the PVYN isolates, reverse transcription-polymerase chain reaction (RT-PCR) and immunocapture-RT-PCR were carried out with specific primers for PVYNTN (3). Both tuber and leaf sap were tested. RT-PCR was performed on tuber sap and immunocapture-RT-PCR on leaf sap. Leaf and tuber sap of healthy, PVY-infected, and PVYNTN-infected tobacco was used in each experiment. At least two tubers from each of 32 PVYN-infected stocks were included in the molecular assay. All samples showed an amplified product of the characteristic size for PVYNTN (835 bp), whereas neither the healthy control nor the PVY sample gave a product. All tested cultivars were infected and all countries from which tuber seed came revealed infected stocks. The high proportion of samples in which PVYNTN was detected suggests that the virus is now endemic to potato-growing regions of northern Italy. The weather in these regions during 1997 was mild and drought in winter-spring and very warm in late summer; these conditions were ideal for disease diffusion by vectors and for symptom development. This is the first report of the occurrence of PVYNTN in Italy. References: (1) C. Kerlan. Le Pomme de Terre Française 498:40, 1997. (2) M. C. Serra and H. L. Weidemann. Plant Dis. 81:694, 1997. (3) H. L. Weidemann and E. Maiss. Z. Pflanzenkrank. Pflanzenschutz 103:337, 1996.

Normal and neoplastic plasma cell membrane phenotype: studies with new monoclonal antibodies.

Three monoclonal antibodies (MoAb), named 8A, 8F6 and 62B1, reacting with plasma cell-associated antigens, were characterized. 8A was found to be positive throughout the B cell lineage maturation steps from the immature B-committed CD10+ cell to the plasma cells. 8F6 and 62B1 reactivity is restricted to more mature cells and related lymphoid malignancies. In particular 62B1 appears to be limited to hairy cells and plasma cells. The results show that it is possible to obtain reagents reacting with plasma cells by immunizing mice with cells derived from human multiple myelomas. Furthermore, the obtained results suggest that it is possible to elicit antibodies against antigens which are present throughout all the differentiation steps of the B cell lineage. These new MoAb could help in elucidating the phenotype of the plasma cells and the relationships of multiple myelomas with other B cell proliferative disorders.