A Case of Rabies With a Prolonged Incubation Period and an Unusual Variation Phenomenon of the Virus Isolated Therefrom

Genetic Characterization of Human Rabies Vaccine Strain in Japan and Rabies Viruses Related to Vaccine Development from 1940s to 1980s

“…After a two-year incubation period, the patient died of rabies in 1948 [ 52 ]. The Takamen strain was isolated from the brain of a mouse that had been highly immunized intraperitoneally twice at a 4-day-interval with the live Takahashi strain obtained from four serial passages in the mouse brain [ 53 ]. The characteristics of the Takamen strain differ from the Takahashi strain distinctly in the short incubation period in rabbits and mice, the high intracerebral infectivity in mice, and the absence of subcutaneous infectivity in rabbits.…”

“…Therefore, it was assumed that the Takamen strain was a viral strain that acquired characteristics very close to those of fixed strains and was fixed during a relatively short period through the passaging [ 54 ]. The Takamen strain was delegated to our facility in 1962 and was conserved in adult mice for 12 passages and in suckling mice for 12 passages before being stocked [ 53 ], the Nishigahara-NIID and Takamen strains showed high identity, with only six amino acid differences ( Table 2 and Figure 3 C). In the 1940s, the Nishigahara strain was used as a veterinary phenolized live vaccine for dogs [ 41 ].…”