No abstract

New antigenic variants of B/Yamagata/16/88-like lineage which appeared in the season of 1997 as a minor strain tended to predominate in the following season. Also, we could observe for the first time, three peaks of activity caused by H3N2 virus and two variants of B influenza virus. Antigenic and phylogenetic analyses revealed that B/Victoria/2/87-like variants appeared again in Japan in 1997 after a nine-year absence. Influenza B viruses evolved into three major lineages, including the earliest strain (I), B/Yamagata/16/88-like variants (II), which comprised of three sublineages (II-(i), II-(ii), II-(iii)), and B/Victoria/2/87-like variants (III). Evolution of influenza B virus hemagglutinin was apparently distinguishable from that of influenza A virus, showing a systematic mechanism of nucleotide deletion and insertion. This phenomenon was observed to be closely related to evolutionary pathways of I, II-(i), II-(ii), II-(iii) and III lineages. It was noteworthy to reveal that the nucleotide deletion and insertion mechanism of influenza B virus completed one cycle over a fifty-year period, and that a three nucleotide deletion was again observed in 1997 strains belonging to lineage II-(iii). It was evident that amino acid substitutions accompanying nucleotide insertions were highly conserved.

The unexpectedly low efficacy of influenza vaccine during school outbreaks of influenza B virus in the spring of 1987 in Japan was probably attributable to a poor antibody response of vaccinees to the epidemic viruses. An antigenic analysis of the causative B viruses isolated in 1987 and 1988 showed much variation in hemagglutination inhibition patterns. The nucleotide sequences that code for the HAl domain of B/

SUMMARYIn 1974 an epizootic occurred among budgerigar flocks in Kunitachi, Tokyo, and a causative agent which possessed haemagglutinating, neuraminidase, and haemolytic activities was isolated from the lung of a dead budgerigar. This agent was IOO to 3o0 nm in diameter and pleomorphic. The width of the ribonucleoprotein was estimated to be about 2o nm. These results indicated that the virus, designated Kunitachi virus, was a member of the paramyxovirus group. The virus contained in the amniotic fluid from infected embryonated hen's eggs, however, at times displayed no haemagglutinating activity with different erythrocytes and complete haemagglutination could only be detected in purified preparations. The Kunitachi viruses including three strains recently isolated from the same host were found to be serologically distinct from the known paramyxovirus strains and appeared to constitute a new subtype of avian paramyxovirus.

The Abbott Determine TP test was an easy and accurate test that could facilitate rapid detection of syphilis in at-risk patients.