A severe respiratory tract infection of cattle characterized by
respiratory and nervous symptoms occurred in the Edinburgh area in
the period Mid -December 1966 to January 1967. During the early
phase of the outbreak, nine viral isolates were recovered from
post mortem material at the Veterinary Investigation Centre,
Edinburgh. These included isolates from the brain, frontal sinus
and trachea. Four further isolates from the nasal passages were made from cattle during this time at the farm.
1. Virus was isolated from two of four convalescing animals
( 7F42 and 7F73 ) brought to the institute for neuropathological
examination. Isolations of virus were made exclusively from
the respiratory passages of these two animals.
2. Three of the isolates, 02/66 a neurogenic strain and two
respiratory strains C1/66 and 7F73/1 recovered from animals
involved in this outbreak were characterized. They were lipid
sensitive, acid labile and showed enhanced inactivation to heat
at 500C for 1 hour in the presence of 1M MgCl2. The structure
of the virus particles was similar to the virion of herpes
simplex and IBR virus. The three isolates produced a similar
cytopathic effect in calf kidney cells consisting of rounding
of cells and intranuclear inclusions. Antigenically they
were similar to the Oxford strain of IBR. virus. It was concluded that the Edinburgh strains were strains of IBR virus.
3. Paired serum samples and single serum samples collected from
cattle in the affected farm were assayed for IBR neutralizing
antibody, by tube neutralization and plaque neutralization
a) Neutralizing antibody titres were low < 1:4 to 1:13.3 when
tested by the conventional tube neutralization method.
b) No significant rises of antibody were observed in the
paired serum samples tested.
4. Neutralizing antibody in three of the same paired serum samples
and 3 single serum samples were examined by the plaque neutralization method. It was found that:
a) This method was more sensitive for detecting neutralizing
antibody to this virus.
b) A slowly rising antibody was observed in 1 paired serum