2.1 Ethics statement and facility.
All animal experiments were carried out in strict accordance with the
recommendations in the Guide for the Care and Use of Laboratory Animals
of the Ministry of Science and Technology of the People’s Republic of
China. All studies were conducted in a biosecurity level 2 laboratory
approved for such use by the Harbin Veterinary Research Institute (HVRI)
of the Chinese Academy of Agricultural Sciences (CAAS). The protocol was
approved by the Committee on the Ethics of Animal Experiments of the
HVRI of the CAAS.