In an infants' ward, gastroenteritis occurred in five children in two groups, probably by nosocomial spread of adenovirus 31 (three cases) and adenovirus 31 + rotavirus (two cases). The infants recovered well. The DNA of adenovirus 31 isolates was analysed with ten restriction endonucleases and found identical for all five strains, but different from the prototype.

Two monoclonal antibodies (MAbs) to cucumber mosaic virus (CMV) were selected from a panel of MAbs for use in the direct DAS (double antibody sandwich)‐ELISA. Two different test procedures were developed: an ELISA with polyclonal and monoclonal antibodies (mixed ELISA) for the routine detection of CMV and a MAb‐ELISA with two MAbs directed against different epitopes for the specific detection of the N serotype which is prevalent in GDR. The conventional two‐step incubation of plates precoated with IgG was compared with simultaneous incubation of test sample and labelled antibody (one‐step incubation). The mixed ELISA proved to be more sensitive than the direct DAS‐ELISA with polyclonal antisera in detecting CMV in crude sap of infected plants. On the other hand, the MAb‐ELISA could be used for serotyping of CMV isolates which is important in epidemiological investigations and in resistance breeding. Both the two‐step and the one‐step procedures gave similar results with some advantages of the latter procedure. One‐step incubation is not only time‐saving but seems to be also more sensitive with regard to the detection limit. However, care must be taken to circumvent the hook‐effect occurring at high virus concentrations.

The cross‐reactivity of two polyclonal antisera with various members of the Potyviridae was determined using four different serological methods. An antiserum (no. 314) prepared against apparently intact turnip mosaic potyvirus (TuMV) particles showed a high cross‐reactivity with all of 20 aphid‐borne potyviruses tested as well as the mite‐borne ryegrass mosaic rymovirus (RGMV) and the fungus‐borne barley mild mosaic bymovirus (BaMMV) with two of the four methods used (indirect PTA‐ELISA or IEM and Western blotting). In immunoelectron microscopic decoration, about two thirds of the viruses tested reacted positively whereas in the direct DAS‐ELISA only the homologous TuMV reacted positively. Another antiserum (no. 203) produced by using as immunogen a mixture of the dissociated core proteins of three trypsin‐treated potyviruses (potato A and V and plum pox viruses), reacted positively in both indirect ELISA and Western blotting with all aphid‐borne potyviruses and RGMV. No reactions were obtained with the other two methods. The causes for these different reactivities are discussed. Both antisera are useful for the detection of aphid‐borne potyviruses, but one (no. 314) is especially suitable for the detection of these viruses under routine conditions by use of a simple indirect PTA‐ELISA.

No abstract

ln attempts to use cross-reacting antibodies for the broad-spectrum detection of potyviruses, two broad-spectrum immunoreagents, the monoclonal antibody P-.^-3H8 and antiserum TuMV-3I4raised against an isolate of peanut stripe virus and turnip mosaic virus, respectively, were examined for their ability to detect members of the Polyriridae in a simple indirect plate-trapped antigen (PTA) ELISA. Both immunoreagents reacted strongly not only wilh isolates of 50 different virus species of the genus Posyrirux but also with several isolates of ryegrass mosaic virus, the type member of the genus Ryinovirm. A few members of the genus Po!yvirus as well as agropyron mosaic and hordeum mosaic viruses, two other species of the genus Rymoviru.s. did not react with P-3-1H8 but only with TuMV-314 which showed the highest degree of cross-reactivity. In no case were positive reactions obtained with nnembers of the genera Byniovints and fpontorirus. These two immunoreagents which appear to be directed to conserved epitopes gave good results when they were employed for detecting potyviruses m field samples from ornamental (Liliales) and leguminous plants. The potential and limitations of cross-reactive antibodies for the routine detection of potyviruses are discussed.