cDNA clones of the largest RNA transcript of the canine distemper and measles morbilliviruses were characterized. This presumably codes for the L protein of these viruses. mRNA 4 was identified as ...coding for the haemagglutinin protein of measles virus. From an analysis of readthrough transcripts representing tandem copies of two or three genes we established a transcriptional map and the gene order on the negative strand genome of the morbilliviruses to be 3'-N-P + C-M-F-H-L-5'. The data exclude the presence of small intervening genes between the six major genes of morbilliviruses and indicate the gene order to be similar to that of Sendai virus and different from that of simian virus 5.
Cultivation of measles virus (SSPE virus, Lec strain) persistently infected C6 rat glioma cells at 39 degrees C resulted in the loss of detectable expression of measles virus proteins. Temperature ...shift-back led to reactivation of measles virus even after maintenance of the cells at 39 degrees C for 15 days. In Northern blot analysis viral mRNA disappeared at 3 days after shift-up whereas 50 S viral genome-sized RNA was detectable until 6 days. The 50 S RNA decreased in quantity in rough correlation with dilution by cell passage at 39 degrees C. The 50 S viral RNA was found in the nucleocapsid fraction. On day 9 after shift-down of persistently infected cells, maintained at 39 degrees C for 15 days, 50 S viral RNA reappeared although mRNAs were not yet detected. Infectious center assays showed that the number of cells in the population at 39 degrees C, which contained an SSPE virus genome that could be reactivated, declined after temperature shift. Moreover, cell cloning experiments, in which single cells of cultures maintained for various lengths of time at 39 degrees C were incubated at 35 degrees C and examined by immunofluorescence, reconfirmed the above results. This indicates that the reactivation of SSPE virus described here was due to re-infection of virus-antigen negative cells with progeny virus produced by a few latently infected cells in the population. The biological significance of this phenomenon in the central nervous system virus infection is discussed.
Hybrid plasmids containing sequences corresponding to four different regions of the measles virus genome inserted in pBR322 were obtained by use of polyadenylated 50 S viral RNA as template for ...reverse transcription. One class of plasmids contains inserts corresponding to the 3' terminal region of the virus genome. The sequence of one of these inserts (605 nucleotides) partially overlaps with the cloned cDNA sequence corresponding to a part of the nucleocapsid protein (N) mRNA (M. Gorecki and S. Rozenblatt (1980). Proc. Natl. Acad. Sci. USA 77, 3686-3690). This insert region shows only one long open reading frame defining the N-terminal part of the nucleocapsid protein. The nucleocapsid protein mRNA starts at about 60 nucleotides from the genome end as revealed by nuclease S1 mapping. Three other classes of plasmid clones contain inserts derived from unidentified regions of the viral genome; they hybridize with viral mRNA species less abundant than those from which cDNA clones have been isolated so far (S. Rozenblatt, C. Gesang, V. Lavie, and F. S. Neumann (1982) J. Virol. 42, 790-797.
A recent examination of measles virus mRNA molecules has shown that the nucleocapsid and haemagglutin messengers are of the size expected from a consideration of their protein products. How ever, the ...mRNA for membrane protein is approximately 50% larger than the size required. The molecular weight of matrix protein has been determined by SDS-polyacrylamide gel electrophoresis, and this procedure can lead to an underestimation of the true size of hydrophobic molecules which show increased SDS binding. It is therefore appropriate to examine the molecular weight determination of this protein to exclude such an artefactual discrepancy in mRNA and protein sizes. We report here that measles virus membrane protein does not shown such anomalous behaviour and confirm that the size discrepancy is a true phenomenon.
The humoral immune response in sera and cerebrospinal fluids (CSFs) of dogs with various forms of canine distemper virus (CDV)-induced encephalitis was assessed by immunoprecipitation of ...radiolabelled nucleocapsid, phosphoprotein, membrane (M), haemagglutinin and fusion proteins. Sera from vaccinated dogs and hyperimmune sera contained antibodies to all the above antigens. In two cases of old dog encephalitis the sera and CSFs showed a restricted response to the M protein of CDV, whilst in three other cases of old dog encephalitis, two cases of chronic distemper (meningo-) encephalitis and experimentally induced encephalitis the humoral immune response appeared to be directed primarily to the nucleocapsid, phosphoprotein and the M protein but not the haemagglutinin or fusion proteins. Precipitation of the M protein by most of the sera was observed only when the antigen had been prepared by in vitro translation.
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