9 CFR § 113.205 - Newcastle Disease Vaccine, Killed Virus.
Newcastle Disease Vaccine (Killed Virus) shall be prepared from virus-bearing tissues or fluids obtained from embryonated chicken eggs or cell cultures. With the exception of § 113.200(c)(2)(iii), each serial shall meet the applicable general requirements prescribed in § 113.200 and special requirements prescribed in this section. A serial found unsatisfactory by a prescribed test shall not be released.
(a) Safety test. The prechallenge part of the potency test in paragraph (b) of this section shall constitute a safety test. If unfavorable reactions attributable to the product occur in any of the vaccinates, the serial is unsatisfactory. If unfavorable reactions which are not attributable to the product occur, the test shall be declared a No Test and may be repeated: Provided, That, if the test is not repeated, the serial shall be declared unsatisfactory.
(b) Potency test. A vaccination-challenge test shall be conducted using susceptible chickens 2 to 6 weeks of age at time of vaccination, properly identified and obtained from the same source and hatch.
(1) Ten or more chickens shall be vaccinated as recommended on the label and kept isolated under observation for at least 14 days.
(2) After at least 14 days post-vaccination, the vaccinates and at least 10 unvaccinated chickens that have been kept isolated as controls shall be challenged with a virulent strain of Newcastle disease virus supplied by or approved by Veterinary Services and the vaccinates observed each day for 14 days.
(3) If at least 90 percent of the controls do not show typical signs of Newcastle disease or die, the test is a No Test and may be repeated. If at least 90 percent of the vaccinates do not remain normal, the serial is unsatisfactory.