Résumé de : MARTIN (M) - 1969 - Analyse des populations virales obtenues par la méthode des plages avec la souche française du virus amaril viscérotrope. Annales de l'Institut Pasteur, 116 (3): pp. 391-403.

SUMMARY.
AN ANALYSIS OF THE PLAQUED POPULATIONS IN THE FRENCH VISCEROTROPIC STRAIN OF YELLOW FEVER VIRUS
Neurovirulencc of viral populations was studied with an in vivo marker, the N marker, characterizing the difference between titers obtained in mice inoculated by intracerebral route and mice inoculated by intraperitoneal route.
The N value of 17 plaques appeared to be inferior to 0.7 log, which indicated a pronounced neurotropism, similar to that of the French neurotropic strain of Yellow Fever.
Difference superior to 0,7 log was found with 23 plaques, because of their low parthogenicity those populations could be connected with certain strains of 17 D virus studied by Theiler with the same in vivo marker.
No neurotropism was found in the progeny of one plaque when inoculated by intraperitoneal route, and this inoculation immunized against, 1,8 log of French neurotropic virus.
Another plaque was slightly pathogenic by intracerebral route, and not at all by peripheral route, but it induced no immunity.
Cloning the less neurotropic populations from the first passage of a virus in tissue culture would then make possible to select more rationally and more rapidly, modified strains for vaccination purposes.