Now the incubation period in mice is used as a measure of the degree of neurotropism for these animals.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

At intervals, monkeys were inoculated intracerebrally to determine the neurotropism of the cultivated virus.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

Occasionally, however, for some unknown reason, a mutant appears with marked reduction in both neurotropism as well as viscerotropism.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

This attenuation consisted in a partial loss of neurotropism for mice and monkeys, as well as a marked loss of viscerotropism for monkeys.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

Fox and his co-workers, the virus had regained some neurotropism so that it actually produced encephalitis in a small proportion of persons vaccinated.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

On the contrary, it appeared that an actual increase of neurotropism had taken place in all three parallel cultures, irrespective of the quantity of nervous tissue in the medium.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

In the 1940's the belief in the neurotropism of the virus began to falter, however, and Enders, Weller and Robbins decided to repeat Sabin and Olitsky's experiment with an improved technique.    From Wordnik.com.  [Nobel Prize in Physiology or Medicine 1954 - Presentation Speech] Reference

In the culture experiments with the JSS strain, maintained for over three hundred subcultures in the same media as were used for the French virus, the neurotropism tended to decrease in all three series.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

These results suggested that the amount of nervous tissue was the conditioning factor which produced the change, as loss of neurotropism occurred only in a medium containing minimal amounts of nervous tissue.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

While it was plain that the viscerotropic affinity could be readily reduced either by mouse brain passage or by prolonged tissue culture, what was particularly desired was a method of reducing the neurotropism.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference

In like manner, the other two strains, which, it will be recalled, produced fatal encephalitis in monkeys at the beginning of these culture experiments, did not lose their neurotropism even though maintained for more than 200 subcultures in a medium containing minimal amounts of nervous tissue.    From Wordnik.com.  [Max Theiler - Nobel Lecture] Reference