The Development of a Vaccine against Avian Infectious Laryngotracheitis IV. Immunization of Chickens with a Modified Laryngotracheitis Vaccine in the Drinking Water

Molecular epidemiology of infectious laryngotracheitis: a review

“…In 1969 the use of the CEO-attenuated Hudson strain was described for ocular, intranasal, or intratracheal vaccination (Hudson, 1969). In Israel, viruses from acute field cases of ILT were attenuated by chorioallantoic membrane passages and resulted in the CEO Samberg strain intended for intra-ocular or vent-brush application (Samberg & Aronovici, 1969a). In 1966, an Australian field isolate attenuated by serial passages in chick embryos resulted in the CEO SA2 vaccine strain.…”

“…However, as early as 1969 failures to vaccinate all birds uniformly by the drinking water vaccination method allowed vaccine strains to regain their virulence while circulating in unvaccinated birds (Samberg & Aronovici, 1969b;Samberg et al, 1971). Back passage of the CEO vaccine viruses through inadequately vaccinated flocks with concurrent reversion to virulence remains one of the main sources of GaHV-1 outbreaks in the USA and worldwide.…”

Virulence of five live vaccines against Avian Infectious Laryngotracheitis and their immunogenicity and spread after eyedrop or spray application

“…imply complete absence of spread after the initial virus multiplication following vaccination: sentinel birds in contact with vaccinates from 26 weeks PV became seropositive, indicating a carrier state of vaccine virus as well. From the published data on onset of immunity (1,5,19), it can be concluded that protection induced by eyedrop vaccination is present in the sinus earlier than in the trachea. Our studies confirmed this.…”

“…Following the isolation of mildly virulent field strains and the attenuation of virulent strains in the fifties and sixties, ocular application became possible and this method soon found general acceptance (1, 2,4,11,19,21,22). Mass-application methods such as drinking water or spray vaccination have been used with these strains too, but as their results, especially under field conditions, were variable (6,7,8,20), they did not gain wide acceptance and eyedrop vaccination has remained the recommended method.…”

“…Mass-application methods such as drinking water or spray vaccination have been used with these strains too, but as their results, especially under field conditions, were variable (6,7,8,20), they did not gain wide acceptance and eyedrop vaccination has remained the recommended method. Since older data on vaccination against ILT refer mainly to methods other than primary eyedrop vaccination and the more recent, relevant data does not provide all the information necessary to draw up a vaccination programme, an evaluation of a selected number of commercial vaccines was considered desirable.…”