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M Mackett

Publications and source records attributed to M Mackett.

56 records · Page 4Linked to original sources
PubMed1979

Restriction endonuclease analysis of red cowpox virus and its white pock variant.

The DNA of red cowpox virus strain Brighton or its white pock variant was analysed by cleavage with restriction endonucleases HindIII, XhoI, PstI or KpnI. Physical maps were constructed and the genomes compared with that of vaccinia virus strain DIE. The size of the red cowpox genome is 23 to 29 megadaltons greater than that of vaccinia and results from the presence of additional, near terminal sequences. An internal region of about 75 megadaltons appears to be highly conserved between the two viruses. The red cowpox genome contains near terminal, repetitive sequences which have some homology with those of vaccinia virus DNA. Rapid renaturation of red cowpox terminal restriction fragments indicates that these are covalently cross-linked. Viable white pock variants arise continually and map as deletion mutants lacking similar sequences from one specific terminus only of the parental genome. The deletion represents 11 to 12% of the red cowpox DNA and includes the terminal repetition which therefore is not required for replication. The deleted terminus of the white pock variant genome does not appear to be cross-linked.

Base Sequence↗
PubMed1979

Conservation and variation in Orthopoxvirus genome structure.

Orthopoxvirus DNA from representative strains of rabbitpox, vaccinia, monkeypox, variola, cowpox and ectromelia viruses was analysed by cleavage with restriction endonucleases HindIII, XhoI or SmaI. Genome mol. wt. vary from about 120 x 10(6) for rabbitpox to about 145 x 10(6) for cowpox. Physical maps of cleavage sites are similar and characteristic for strains of the same Orthopoxvirus type. The distribution of HindIII sites suggests that an internal region of mol. wt. about 30 x 10(6) is highly conserved between Orthopoxvirus genomes although some type-specific differences occur within this region, especially with strains of ectromelia virus. Conservation of internal sequences is less marked following analysis with XhoI although cleavages within this central region of particular genomes appear to represent a subset of preferred sites. Endonuclease SmaI cleaves exceptionally infrequently and distinguishes variola, monkeypox, vaccinia, cowpox or ectromelia viruses. Type specific differences result largely from extensive, near terminal variations in length and sequence. Representative Orthopoxvirus genomes have rapidly renaturing terminal restriction fragments confirming the presence of near terminal, covalent cross-links. Terminal restriction fragments from the same or different genomes generally cross hybridize indicating the presence of near terminal repetitions of mol. wt. up to 6 x 10(6) and which share at least a subset of common sequences. Variola strains however, appear to lack such sequences from one specific terminus which maps shorter than that of related viruses.

Base Sequence↗