McDonald V, Ballingall S
Parasitology. 1983 Jun;86 (Pt 3):361-9. doi: 10.1017/s0031182000050551.
Attenuated lines of Eimeria acervulina were isolated between 62 and 72 h post-infection from the Houghton (H) strain. The inoculation of small numbers of oocysts of precocious (HP) lines gave substantial protection to Light Sussex chicks kept on litter against challenge with the virulent H strain. The precocious trait of the 72 h HP line was shown to be stable because the kinetics of oocyst production remained unaltered after 9 consecutive passages through birds in which only late developing oocysts were used for passage. The precocious 62 h HP line was subjected to further selection for 5 consecutive passages. The resultant (62 A HP) line was shown to be more attenuated than the 72 h HP line but remained capable of immunizing chicks against challenge with the H strain.
堆型艾美耳球虫减毒株是在感染后62至72小时从霍顿（H）株中分离出来的。接种少量早熟（HP）株的卵囊，能为饲养在垫料上的轻型苏塞克斯雏鸡提供显著保护，使其免受强毒H株的攻击。72小时HP株的早熟特性被证明是稳定的，因为在连续9代通过仅使用发育后期卵囊进行传代的鸡后，卵囊产生的动力学保持不变。早熟的62小时HP株连续传代5次进行进一步选育。结果得到的（62A HP）株比72小时HP株的毒力更弱，但仍能使雏鸡对H株的攻击产生免疫。
