Tadashi Imagawa

Oka varicella vaccine is distinguishable from its parental virus in DNA sequence of open reading frame 62 and its transactivation activity

When the nucleotide sequences of the Oka vaccine and its parental varicella‐zoster virus (VZV) were compared in 6 open reading frames (ORFs), glycoprotein C (gC) and 5 transactivator genes, mutations were detected only in the immediate‐early gene 62. The vaccine virus contained a mixture of different sequences that had variations at 15 nucleotide positions, but only one sequence was found for the Oka parental virus gene 62. The Oka vaccine virus gene 62 could be distinguished from the parental virus gene using a simplified restriction‐enzyme fragment length polymorphism analysis, using NaeI and BssHII. This analysis was based on the sequence data obtained in this study. Studies of the regulatory activities of the ORF62 gene product (IE62) in a transient transfection assay indicated that IE62 of the parental virus had a stronger transactivational activity than that of the vaccine virus in activating immediate‐early, early, and late gene promoters. These data suggest that IE62 might play an important role in the attenuation of VZV. J. Med. Virol. 61:497–503, 2000.

Comparison of DNA sequence and transactivation activity of open reading frame 62 of Oka varicella vaccine and its parental viruses

When nucleotide sequences of Oka vaccine and its parental viruses of varicella-zoster virus (VZV) were compared in 5 open reading frames (ORFs) including glycoprotein C (gC) and 4 immediate-early genes, mutations were detected only in gene 62 which is one of the immediate-early genes. Compared with its parental virus, the vaccine virus contained 15 nucleotide substitutions. With the differentiation method using the simplified restriction-enzyme fragment length polymorphism analysis by Nae I and Bss HII, which was established based on the sequence analysis data in this study, the Oka vaccine virus could be distinguished from its parental virus. Studies of the regulatory activities of the ORF62 gene product (IE62) in a transient assay indicate the IE62 of the parental virus had a stronger transactivational activity than that of the vaccine virus against immediate-early, early and late gene promoters. These data suggest that gene 62 might have an important role for attenuation of VZV. This is the first report in which many substitutions of nucleotides in gene 62 of Oka vaccine virus was found, compared with that of Oka parental virus.

Frameshift mutations resulting in the changes of the same amino acid residue (140) in T4 bacteriophage lysozyme and in vivo codons for Trp, Tyr, Met, Val and Ile.

Abstract The lysozymes of three new strains of double frameshift mutants of T4 bacteriophage, e J37 e JD3, e J200 e JD4 and e J25 e JD1, were isolated from their respective lysates, and their amino acid sequences were compared with that of the wild-type strain. It was found that Trp 138 -Tyr-Asn 140 in wild-type lysozyme changes to Met-Val-Tyr in e J37 e JD3, Tyr 139 -Asn 140 to Cys-Ile-Ile in e J200 e JD4 and Asn 140 to Ile-Ile in e J25 e JD1. From these results, a new hot spot for frameshift mutations has been found at Asn 140 and in vivo codons for Trp, Tyr, Met, Val and Ile are thought to be UGG, UAU, AUG and AUA, respectively. Nineteen in vivo codons out of 64 codons have been identified by these results together with our previous results.

An activity which restores theta toxin activity in some theta toxin-deficient mutants of Clostridium perfringens

Group a mutants of Clostridium perfringens are deficient in theta toxin but release a dialyzable substance (“substance A”), which restores theta toxin activity to group b mutants, into a culture supernatant; group b mutants are defective in “substance A” release. “Substance A” activity appeared in the exponentially growing phase of group a mutants and disappeared in the stationary phase. “Substance A” activity was most stable at pH 5.0 and 0 C and even increased threefold in the first 5 hr, but gradually decreased during the following 15 hr. It was quickly inactivated at neutral and higher pHs at 0 C.