Adaptation scheme for mall/178 H2N2. Quail and White Leghorn chickens were infected with mall/178 H2N2 and were then tested for replication and transmission. Mall/178 replicated but was not transmitted in quail; in chickens, it neither replicated nor was transmitted. Steps were taken to adapt this mall/178 virus by passage in quail, using lung homogenates from the previous passage as the viral inoculum. At the sixth passage of lung homogenates, transmission in quail was tested. Respiratory transmission was observed, and this quail-adapted virus was designated qa-mall/178. Chickens were then infected with qa-mall/178, and both replication and transmission were tested. Qa-mall/178 not only replicated but also was transmitted in chickens. This virus was transmitted via the fecal-oral route, and therefore, steps were taken to adapt this virus in chickens so as to produce respiratory shedding. After seven passages, a chicken-adapted qa-mall/178 virus (ch-qa/178) was isolated; it was found to replicate in the lungs and to be transmitted via the respiratory route in chickens while maintaining its ability to replicate and be transmitted in quail.