- Volume 51, Issue 1, 1980

After multiplication in the continuous human cell lines HeLa, KB, and Hep 2, echovirus 11 (prototype strain Gregory) loses its haemagglutinating (HA) activity but retains infectivity. After seven passages in Hela cells the HA activity was not restored. There was no correlation between the loss of HA activity and modification of thermosensitivity, plaque morphology, surface properties and antigenicity. HA− echovirus 11 particles did not show the properties of defective interfering (DI) particles as described for poliovirus.

We report for the first time the replication of infectious adeno-associated virus type 1 (AAV-1) in rodent cells [primary mouse kidney (PMK) and mouse L929 cells] using murine adenovirus (MAV) as a helper virus and also the production of AAV-1 virus antigen by herpes simplex virus type 1 (HSV-1) with its temperature-sensitive mutant ts 200 in mouse neuroblastoma (NB) cells. The infectious AAV virions produced by MAV on L cells had a buoyant density of 1.41 g/ml in caesium chloride gradients.

Polystyrene microtitre plates coated with bovine C1q were used to trap antigen: antibody aggregates of three plant viruses [plum pox virus (PPV), potato virus Y and cocksfoot mild mosaic virus] and human antibody aggregates in an ELISA-type system. The aggregates were detected with alkaline phosphatase-labelled anti-rabbit or anti-human IgG. The assay was as sensitive as the double antibody sandwich method of ELISA for the detection of PPV particles; the limit of detection was 4 to 15 ng virus/ml in purified preparations or a dilution of > 1/1000 in infective Nicotiana clevelandii sap extracts. When used at low dilutions, plant sap of three of the four species tested had an inhibitory effect on the reaction.