title: Effect of multiple cell culture passages on the biological behaviour of chicken anaemia virus.
abstract: The Cux-1 isolate of chicken anaemia virus (CAV) was passaged over 320 times in Marek's disease virus transformed chicken lymphoblastoid (MDCC-MSB1) cells. Comparison of the infectivity titres of virus pools derived from viruses that had received 0 (P0), 49 (P49), 170 (P170) and 320 (P320) passages in our laboratory indicated that the yields of infectious virus increased over 100-fold with passage number from P0 to P170. P320 exhibited unusual cell culture growth characteristics in that, unlike its lower passage counterparts, virus-specific immunofluorescence (IF) and cytopathic effect were detected at very low levels at 2 days post infection, with an additional passage of infected cells into fresh medium being required to produce high levels of infectious virus. Experimental infection of 1-day-old SPF chicks showed that P170 and P320 were substantially attenuated compared to P49 and a pathogenic, low-passage isolate used as control. When assessed by the indirect IF test, infection of 1-day-old chicks with the P49 and P170 isolates elicited similar levels of CAV-specific antibody to those elicited by infection with the pathogenic, low-passage virus and higher than those elicited by infection with the P320 isolate. Experimental infection of 5-week-old chicks indicated that the attenuated P170 and P320 isolates invoked similar CAV-specific antibody levels to those invoked by the pathogenic P49 and control isolates.
authors.affiliation: Department of Agriculture for Northern Ireland, Queen's University of Belfast, Veterinary Sciences Division, Stormont, Belfast, UK.
authors.forename: D
authors.initials: D
authors.lastname: Todd
authors.forename: T J
authors.initials: TJ
authors.lastname: Connor
authors.forename: J L
authors.initials: JL
authors.lastname: Creelan
authors.forename: B J
authors.initials: BJ
authors.lastname: Borghmans
authors.forename: V M
authors.initials: VM
authors.lastname: Calvert
authors.forename: M S
authors.initials: MS
authors.lastname: McNulty