The porcine paramyxovirus is a newly identified agent of a fatal disease in piglets, endemic in Mexico since 1980 Analysis of nucleocapsids obtained from purified virus or from a permanently infected cell line revealed one major band with an M~ of 68K, the nucleoprotein. Two other proteins were also identified, the large protein and the matrix protein, with apparent Mr of about 200K and 40K, respectively. The protein migration pattern of LPMV was compared, by SDS-PAGE, with that of Newcastle disease virus, bovine parainfluenza 3 virus and Sendai virus. Differences in the Mr of LPMV proteins and the proteins of these paramyxoviruses were observed. We propose that LPMV should be classified as a novel member of the genus Paramyxovirus.

The complete nucleotide sequence of the gene encoding the matrix protein (M) of the porcine paramyxovirus LPMV has been determined. The gene is 1376 nucleotides long including 5' and 3' non-coding sequences with a protein-coding sequence of 1107 nucleotides. The deduced protein, containing 369 amino acids with a calculated Mr of 41657, is hydrophobic overall with a net positive charge of +17.5. Comparative sequence analysis revealed high amino acid homology to other paramyxovirus M proteins, with the highest degree of identity (46 %) with the human mumps virus. This is strong evidence that the porcine paramyxovirus LPMV is a genuine member of the paramyxovirus genus.

The complete nucleotide sequence of the haemagglutinin-neuraminidase (HN) gene of the porcine paramyxovirus LPMV, was determined from cDNA derived from viral genomic RNA. The gene was 1906 nucleotides long including a putative gene end and poly A signal. One long open reading frame was found encoding a protein of 576 amino acids with a calculated molecular weight of 63,324. The protein contains four potential N-glycosylation sites and a major hydrophobic region near the N-terminal, suggesting a membrane anchor domain. Comparison of the deduced amino acid sequence of the LPMV HN protein with that of other paramyxovirus HN proteins, revealed the highest amino acid identity to simian virus 5 of 43% and mumps virus of 41%.

Complementary DNA clones representing the fusion (F) protein gene of the porcine rubulavirus LPMV were isolated and sequenced. The F gene was found to be 1,845 nucleotides long containing one long open reading frame capable of encoding a protein of 541 amino acids. The cleavage motif for F0 into F1 and F2 is His-Arg-Lys-Lys-Arg. A sequence comparison and a phylogenetic analysis was performed in order to identify possible functional domains of paramyxovirus fusion proteins and also to classify the porcine rubulavirus. The F gene of LPMV is most closely related to the human mumps virus and simian virus type 5 F genes, and is therefore classified into the rubulavirus genus. A coding region for a small hydrophobic protein was however not found between the F and hemagglutinin-neuraminidase (HN) genes as previously found in both SV5 and mumps.

The acyclic guanosine analogs R-and S-enantiomers of 9-(3,4-dihydroxybutyl)guanine [(R)-and (S)-DHBG], 9-(4-hydroxybutyl)guanine (HBG), and 9-(2-hydroxyethoxymethyl)guanine (ACV) were examined for their effects on human cytomegalovirus (CMV) replication and on CMV DNA synthesis in cell culture as well as for their ability as triphosphates to interact with CMV DNA polymerase. Production of early CMV antigens was not affected. All analogs inhibited CMV DNA synthesis and late viral antigen synthesis. Primary CMV isolates were less susceptible to all tested analogs than was the laboratory strain CMV Ad.169. The triphosphate of ACV was the most potent inhibitor of CMV DNA polymerase, with an observed Ki of 0.0076 ,uM. The corresponding Ki values of the triphosphates of (R)-DHBG, (S)-DHBG, and HBG were 3.5, 13.0 and 0.23 ,uM, respectively. All triphosphates of the analogs given above inhibited CMV DNA polymerase in a competitive manner with respect to dGTP. The triphosphates of the analogs also inhibited reactions when the synthetic template poly(dC)oligo(dG)1218 was used, whereas no inhibition was observed with poly(dA)oligo(dT)12-18None of the triphosphate analogs supported DNA synthesis in the absence of dGTP, showing that no analog was an alternative substrate to dGTP.Several nucleoside analogs are selective inhibitors of viral replication at concentrations that do not affect host cells. Two classes of nucleoside analogs have received particular attention: 5-substituted 2'-deoxypyrimidines (3) and acyclic guanosine analogs (4). They are strongly active against herpes simplex virus (HSV) types 1 and 2 (HSV-1 and HSV-2). A general property of these analogs is postulated to be a selective phosphorylation to monophosphates by the HSV-induced thymidine kinase (TK), followed by preferential inhibition of HSV-induced DNA polymerase activity by the triphosphorylated forms (3,4,8,13,20). Human cytomegalovirus (CMV) lacks a virus-encoded TK (7, 29). Therefore, one would expect the acyclic nucleoside analogs, which do not seem to be substrates for cellular TK, to remain unphosphorylated in CMV-infected cells and thus not to be inhibitors of CMV replication. Acyclic nucleoside analogs have been reported to have lower activities against CMV than against HSV or varicella zoster virus (1, 10). Therefore, it was surprising that 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG) was a much more potent inhibitor of CMV multiplication in cell culture than 9-(2-hydroxyethoxymethyl)guanine (ACV) (18, 24). The triphosphates of these analogs, DHPGTP and ACVTP, were inhibitors of the partially purified CMV DNA polymerase. ACVTP had a higher affinity than DHPGTP for the CMV DNA polymerase (19). Higher amounts of DHPGTP, however, were formed in CMV-infected cells compared with those of ACVTP (2). This probably explains the better activity of DHPG, but the enzyme which mediates monophosphorylation of DHPG still has not been defined.In this study we investigated several acyclic guanosine analogs, the R-and S-enantiomers of 9-(3,4-dihydroxybutyl...