| Yellow fever virus is the type species of the Group B arboviruses, or flavi- viruses. The type strain is the Asibi strain b(reference  ), a viscerotropic strain which has been maintained by serial passage in rhesus monkeys in which it produces a fatal illness  ,  . The 17-D vaccine strain is derived from the Asibi strain by serial passage in tissue culture and in embryonated eggs  . The 17-D derivative appears to have an extra antigen not present in the parent strain nor in other yellow fever strains. Avian leukosis virus contaminated early 17-D vaccines, but leukosis-free vaccine is now prepared. |
| The French or Dakar viscerotropic strain  was adapted, after a few monkey passages, to mouse brain  . The resulting French Neurotropic strain (FN) is widely used in mouse neutralization tests. A high mouse passage FN strain has been used by the French for vaccination. 17-D virus passaged in mice has also been used as a vaccine. |
| Strains of yellow fever virus isolated in America lack an antigen present in African strains  . |
| For further reading on the early history of yellow fever see References  ,  ,  ,  . For a more recent discussion see Reference  . |
|  not only confirmed the contention of Carlos Finlay that yellow fever was transmitted by Aedes aegypti but also demonstrated that the causative agent was filterable and thus were the first to show that a disease in man was due to a virus infection. However, the strain of yellow fever virus that was passed by Reed, et al., from man to man was not transferred to lower animals and was not retained. It would, therefore, seem appropriate to assign the first ""isolation"" of the virus to its continuous passage in monkeys by Stokes, et al.  and to designate Asibi as the prototype strain (R.M.T.). |
b Reed, et al.