- Volume 68, Issue 7, 1987

Caprine herpesvirus 1 (CapHV-1) DNA was examined by electron microscopy, restriction site mapping and homology studies with bovine herpesvirus 1 (BHV-1) DNA. Although the restriction site maps differed significantly, we showed that the genome structures of CapHV-1 and BHV-1 were identical and that the DNAs shared a high degree of base sequence homology.

Nuclei isolated from Trichoplusia ni cells (TN-368) infected with Autographa californica nuclear polyhedrosis virus (AcMNPV) were used to study the replication of viral DNA. Based on DNA: DNA hybridization data, virus-specific DNA polymerase activity was insensitive to aphidicolin and novobiocin and was inhibited by ddTTP and N-ethylmaleimide. The data indicate that the AcMNPV-specific DNA polymerase is a γ-like DNA polymerase which was first detected at 5 h postinoculation.

The two morbilliviruses rinderpest virus (RPV) and peste des petits ruminants virus (PPRV) are closely related and cause severe disease in large and small ruminants, respectively. They show distinct epidemiological patterns and are distinguishable by reciprocal cross-neutralization tests. We have analysed the proteins induced by these viruses in infected cells and have shown that they can be distinguished by a very marked difference in the apparent mol. wt. of the nucleocapsid (N) protein. The N protein of PPRV is almost identical in mobility on polyacrylamide gels to the N proteins of measles virus and canine distemper virus (60K). Several strains of RPV and PPRV from widespread geographical locations were studied and found to show this difference in the N protein.

The protease inhibitor leupeptin prevented multiple step replication of an influenza virus (A/swine/1976/31, H1N1) mediated by staphylococcal proteases. It also suppressed virus replication and development of fatal pneumonia in mice co-infected with the virus and Staphylococcus aureus.

Ten murine monoclonal antibodies (MAbs) specific for a British isolate of potato leafroll luteovirus (PLRV) were produced in large quantities in ascitic fluids and their isotypes determined. All 10 MAbs reacted in indirect ELISA with intact PLRV particles but four did not react with disrupted virus particles, suggesting that these four MAbs are specific for epitopes dependent on quaternary structure. None of the MAbs gave a precipitin reaction in immunodiffusion tests. All the MAbs reacted strongly with, but failed to differentiate, 28 readily aphid-transmissible British PLRV isolates, six of which consistently caused symptoms differing in severity in indicator hosts. Two MAbs (SCR-8 and SCR-10) reacted only weakly with two other PLRV isolates, both of which were poorly transmissible by aphids. Three MAbs (SCR-6, SCR-8 and SCR-10) reacted with groundnut rosette assistor luteovirus (GRAV), but none reacted with British isolates of three other luteoviruses: carrot red leaf, beet western yellows and barley yellow dwarf (B and F isolates). Five epitopes on PLRV particles were distinguished, of which the two that were missing in the poorly aphid-transmissible isolates of PLRV and/or were shared with GRAV were both apparently dependent on quaternary structure.

The nucleotide sequences of the satellite RNAs associated with tomato black ring virus isolates L, G, E and C were determined and compared with the sequence of the satellite associated with strain S determined earlier. The sequence of satellite L closely resembled that of satellite S and both were to a lesser extent similar to satellites G, E and C which themselves were closely similar. There was 90% or more sequence homology between satellites in each group, G and E being the most closely related, with only one nucleotide (nt) difference between them. There was about 60% homology between the groups. Satellites G, E and C had longer 5 ′ non-coding regions (40 nt) than satellites L and S (14 nt), but were shorter by 11 to 13 nt in their 3 ′ non-coding regions. The sequences all contained a single large open reading frame for proteins of mol. wt. 47808 (424 amino acids) (L), 47792 (419 amino acids) (G, E) and 47698 (419 amino acids) (C). The deduced amino acid sequences differed principally in their N-terminal 65 residues. Several regions of sequence comprising 10 or more amino acids, and one of 31 amino acids, were identical in all satellite sequences. No marked sequence similarities were detected between the satellite sequences and a number of viral protein and nucleic acid sequences available in databases. The extent of homology between the 3 ′ ends of satellite sequences and those of RNA-1 or RNA-2 of TBRV was slight, consisting of several hexa- and heptanucleotides.

Pathogenesis-related (PR) proteins (M r 14000 to 18000) serologically related to PR 1a protein from Nicotiana tabacum cv. Xanthi-nc were detected in infected plants or salicylic acid-treated plants of maize, barley, tomato, potato, Solanum demissum, Gomphrena globosa and Chenopodium amaranticolor using affinity-purified antibodies in immunoelectroblots. Only in Go. globosa was a protein related to PR 1a found in a healthy plant.