Characterisation of strains of infectious bronchitis virus isolated in Chile

Abstract

SUMMARYNine isolates of infectious bronchitis (IB)-like viruses were made from 23 flocks (broilers or layers) in Chile experiencing the types of disease problems commonly associated with IBV. Their identity as IB viruses was confirmed. The histological changes they caused in tracheal organ cultures (OC) are described.Serum neutralisation tests performed in embryonated eggs (α-method) suggested that four of the isolates were serologically related to the Massachusetts (Mass) serotype of IBV and one to Connecticut. The four other strains were examined further by a serum neutralisation test in OC (ß-method). One was found to be of the Mass serotype but the others were found to be unrelated antigenically to a wide range of IBV serotypes isolated in many countries over a number of years. One of these three strains and the Mass strain, when given intranasally to 8-day-old specified pathogen free chickens together with pathogenic serotypes of E.coli, caused some mortality and considerable morbidity. The H120 vaccine strain was found not to protect completely against challenge with these four strains 21 days later.

Relationship between sequence variation in the S1 spike protein of infectious bronchitis virus and the extent of cross‐protectionin vivo

“…It has been observed in many studies that an IBV vaccine of a given serotype frequently induces poorer protection against isolates of other serotypes than against isolates of the same serotype (Parsons et al, 1992;Cubillos et al, 1991;Gelb et al, 1989;Picault et ed., 1986;Davelaar et ed., 1984) although, conversely, there are also instances of good cross-protection between different serotypes (Cook et al, 1986).…”

Detection of infectious bronchitis virus

“…Traditionally, strain classification into serotypes has been by VNTs performed in various systems, including embryonated eggs (Dawson & Gough, 1971;Cunningham, 1973;Cowen & Hitchner, 1975;Lohr, 1976Lohr, , 1977Gelb et al, 1981Gelb et al, , 1989Gelb et al, , 1991Davelaar et al, 1984;Picault et al, 1986;Karaca et al, 1990;Cubillos et al, 1991;Capua et al, 1998), cell culture (Hopkins, 1974;Cowen & Hitchner, 1975;Wadey & Faragher, 1981;Csermelyi et al, 1988), or TOCs (Johnson & Marquardt, 1975;Darbyshire et al, 1979;Cook, 1984;Cook et al, 1987Cook et al, , 1999Hinze et al, 1991;Ignjatovic & McWaters, 1991;Cubillos et al, 1991;Parsons et al, 1992;Dhinakar Raj & Jones, 1996b;Ignjatovic & Ashton, 1996;Wang et al, 1997). There are several reports on serotyping by the HI test (Lashgari & Newman, 1984;Brown & Bracewell, 1985;Toro et al, 1987;Cook et al, 1987;Capua et al, 1998Capua et al, , 1999.…”

Breadth of protection of the respiratory tract provided by different live-attenuated infectious bronchitis vaccines against challenge with infectious bronchitis viruses of heterologous serotypes

“…The tracheas were carefully removed and examined for ciliary activity as described previousl y (Cubillos et al, 1991;Cavanagh et al, 1997). Brie¯y, each of 10 explant s prepared from each trachea was examined by low-power microscopy and ciliary activity scored as follows: 0, all cilia beating; 1, 75% beating; 2, 50% beating; 3, 25% beating; and 4, none beating (100% ciliostasis).…”

“…This was followed in the mid-1950s by the Connecticut serotype (Jungherr et al, 1956). Since that time, new IB serotypes have continued to be reported from the US (Gelb et al, 1991), Europe (Davelaar et al, 1984;Cook & Huggins, 1986) and many other parts of the world (Cubillos et al, 1991).…”