Yasushi Ohtsu

Fine Mapping of the Subunit Binding Sites of Influenza Virus RNA Polymerase

Influenza virus RNA polymerase consists of three subunits, PB1, PB2 and PA, and catalyzes both transcription and replication of the RNA genome. PB1 is a catalytic subunit of RNA polymerization and a core of the subunit assembly. The subunit binding sites were mapped at about several hundred amino‐acid size. Fine mapping of the subunit binding sites was determined. The PB1‐PA binding regions were mapped within in the N‐terminal 25 amino acids of PB1 and 668–692 of PA. PB1 and PB2 interacted within wider regions, 600–757 of PB1 and 51–259 of PB2. In these amino‐acid spans, 206–259 of PB2 may be the most important region of PB1 binding and 718–732 of PB1 may be the most important region of PB2 binding because the binding activity was lost when the regions were lost in the subunits. The additional regions contributed to strong binding of these subunits.

Influenza virus RNA polymerase PA subunit is a novel serine protease with Ser624 at the active site

Influenza virus RNA polymerase is a multifunctional enzyme that catalyses both transcription and replication of the RNA genome. The function of the influenza virus RNA polymerase PA subunit in viral replication is poorly understood, although the enzyme is known to be required for cRNA → vRNA synthesis. The protease related activity of PA has been discussed ever since protease‐inducing activity was demonstrated in transfection experiments.

Inhibition of influenza virus replication in cultured cells by RNA‐cleaving DNA enzyme

Influenza virus replication has been effectively inhibited by antisense phosphothioate oligonucleotides targeting the AUG initiation codon of PB2 mRNA. We designed RNA‐cleaving DNA enzymes from 10‐23 catalytic motif to target PB2‐AUG initiation codon and measured their RNA‐cleaving activity in vitro. Although the RNA‐cleaving activity was not optimal under physiological conditions, DNA enzymes inhibited viral replication in cultured cells more effectively than antisense phosphothioate oligonucleotides. Our data indicated that DNA enzymes could be useful for the control of viral infection.

Isolation of Amantadine-Resistant Influenza A Viruses (H3N2) from Patients following Administration of Amantadine in Japan

ABSTRACT In Japan, the use of amantadine for treatment of influenza A virus infection was not accepted until November 1998, although it was widely used for treatment of Parkinsonism. Since then, we have monitored the emergence of amantadine-resistant viruses and isolated two viruses from patients on long-term treatment with amantadine.

Molecular Evolution of Human Echovirus 9 Isolated from Patients with Aseptic Meningitis in Northern Kyushu during the Summer of 1997

An epidemic of aseptic meningitis caused by human echovirus 9 (E‐9) occurred in the summer of 1997 in northern Kyushu, Japan. Sequences of genome position 2504–3358, which encoded a part of VP1, of the nine isolated viruses were determined. An RGD motif and B‐C loop were found in all. They were almost identical and closely related to the virulent strain Barty.

Serologic response after vaccination against influenza (A/H1N1)pdm09 in children with renal disease receiving oral immunosuppressive drugs

A limited number of reports are available regarding the effect of the influenza vaccine in pediatric patients receiving steroid and immunosuppressant therapy. The influenza A(H1N1)pdm09 vaccine was administered to 15 children with renal disease who were receiving steroid and immunosuppressant therapy (treatment group) and 23 children with who were not receiving these drugs (non-treatment group). Titer transition of the hemagglutination inhibition antibody was compared between the 2 groups immediately before vaccination and 4 weeks and 6 months after vaccination. Multivariate analysis showed a significant correlation between geometric mean titer, SCR, and SPR with age, while no correlation was observed between treatment with immunosuppressant therapy and efficacy. No serious adverse reactions occurred after vaccination. This strain is not present in existing influenza vaccines, and A(H1N1)pdm09HA vaccination was administered alone in 2009. The children in this study had not previously been exposed to this strain. Therefore, we evaluated the effect of the A(H1N1)pdm09HA vaccine without the effects of vaccination or past infection with A(H1N1)pdm09HA or A(H3N2) vaccination in the previous year.

Fine mapping of the subunit binding sites of influenza virus RNA polymerase

Influenza virus RNA polymerase consists of three subunits, PB1, PB2 and PA, and catalyzes both transcription and replication of the RNA genome. PB1 is a catalytic subunit of RNA polymerization and a core of the subunit assembly. The subunit binding sites were mapped at about several hundred amino-acid size. Fine mapping of the subunit binding sites was determined. The PB1-PA binding regions were mapped within in the N-terminal 25 amino acids of PB1 and 668-692 of PA. PB1 and PB2 interacted within wider regions, 600-757 of PB1 and 51-259 of PB2. In these amino-acid spans, 206-259 of PB2 may be the most important region of PB1 binding and 718-732 of PB1 may be the most important region of PB2 binding because the binding activity was lost when the regions were lost in the subunits. The additional regions contributed to strong binding of these subunits.

Nucleotide sequence of the gene encoding the RNA polymerase and the 3′ non-coding region of a bovine enterovirus Japanese isolate: rapid synonymous substitutions between European and Japanese strains

SummaryThe nucleotide sequences of the genome RNA encoding the RNA polymerase and the 3′ non-coding region (NCR) of bovine enterovirus (BEV) serotype I Japanese isolate, MZ468, were determined. The genetic distance between the two BEV serotype I strains, MZ468 and VG-5-27, was calculated by pairwise comparison of nucleotide sequences. The synonymous substitution rate was high (1.40 × 10−2/site/year), and of the same order as those of influenza virus HA, HIV-1 gag and env, and enterovirus 70 VP1 genes.