Table 1.

Segregation of resistance and susceptibility to subgroup A and B viruses in F2 progeny obtained by crossing lines 63 and 72

Subgroup B susceptibility phenotypeaNo. of progeny with subgroup A susceptibility phenotypebTotal
SusceptibleResistant
Susceptible452267
Resistant17926
Total6231
  • a Susceptibility to subgroup B viruses was determined by injection of 500 FFU of Bryan high-titer RSV (RAV-2) into the wing webs of 4-week-old chicks. Tumors were scored on the basis of palpation of the wing web at 2, 3, and 4 weeks postinfection.

  • b Susceptibility to subgroup A viruses was determined as described for subgroup B except that Bryan high-titer RSV (RAV-1) was used.