Influenza-B Tokio

Influenza B virus is a member of the Orthomyxoviridae family, which also includes Influenza A and C viruses. Unlike Influenza A, which infects a wide range of animals, Influenza B primarily infects humans and seals . The strain B/Tokio/53/99 is a specific variant of the Influenza B virus, which has been studied for its unique properties and behavior.

The Influenza B virus is an enveloped virus with a multipartite genome consisting of eight segments of linear negative-sense, single-stranded RNA . Each segment is encapsidated in a separate nucleocapsid, and the nucleocapsids are surrounded by an envelope. The virus has approximately 500 surface projections made of hemagglutinin and neuraminidase, which are crucial for the virus’s ability to infect host cells .

The genome of the Influenza B virus is 14,648 nucleotides long . It mutates at a rate 2-3 times lower than Influenza A, but still enough to prevent lasting immunity . This slower mutation rate means that Influenza B evolves more slowly than Influenza A but faster than Influenza C .

The B/Tokio/53/99 strain is typically purified from the allantoic fluid of 10-day-old embryonated eggs inoculated with the virus . The purification process involves ultracentrifugation with a 10-40% sucrose gradient . The final product is a sterile, filtered colorless solution containing 0.1M NaCl, 10mM Tris HCl, 1mM EDTA (pH 8), 0.1% sodium azide, and 0.005% thimerosal .

The B/Tokio/53/99 strain is used in serological studies and as an immunogen for antibody production . It has been tested with anti-influenza B monoclonal antibodies in ELISA assays to confirm its immunological activity .

The B/Tokio/53/99 strain is stable at 4°C for up to four weeks but should be stored desiccated below -18°C for long-term storage . It is important to avoid freeze-thaw cycles to maintain its stability .

Both sodium azide and thimerosal, used in the formulation, are hazardous substances and should be handled by trained staff only . Proper laboratory practices and techniques are required to ensure safe handling and inactivation of the virus .