A brief introduction of Xantek’s
Science & Technology
Origin and provenance
In 1955 in search of the attenuated vaccine strains which could afford the protection in young chicks from Fowl typhoid disease Dr. William, H. Smith had conducted an extensive research program In Houghton Poultry Research Station, United Kingdom. The wild type field strain Salmonella gallinarum 9 (SG9) has been used and was selected by growing in defined medium which gives limited nutrients. A group of rough and smooth mutants were isolated during this study. They were tested for their property of attenuation and immunity in 5-6 weeks old chickens. During this program Dr. Smith had developed an infamous Salmonella gallinarum 9 rough strain (SG9R), this vaccine strain which later has been used by industrial broiler all over the world, the first paper which was published in 1956 by William Smith titled ‘ The use of live vaccines in experimental salmonella gallinarum infection in chickens with observations on their interference effect’ J Hyg (Lond). 1956 Sep;54(3):419-32. SG9R showed a good immunity in young chicks against oral infections with Salmonella gallinarum, and the most important fact is that SG9R did not produce demonstrable agglutination in chickens, was no lethal for a day old chicks, and did not have serology interfere with production in laying hens.
Dr. William Smith was known as most proliferate scientist and published over 80 scientific paper and books during his academic career. He was Fellow of Royal Society UK. He was also know as scientific promoter and philanthropist as he does not believe that scientific discovery should be commercialised or become money generator if it is used for cure or prevent human and animal disease. In 1978 during the collaboration work with Cooper Animal health he donated this vaccine strain to the company in order it can be produced into industrial scale for widely use in poultry industry.
The original antibiotic-sensitive mutant SG9R was derived from the parental strain Salmonella Gallinarum 9 isolated from a case of field fowl typhoid, described by Smith (1955) and known to produce fowl typhoid in experimental infections (Smith, 1955; Barrow et al., 1987). As can be seen it has maintained its virulence over many years.
The SG9R mutant was produced by passage in defined medium in vitro together with a smooth strain SG9S, both of which were described by Smith (1956). Although the level of protection produced by the SG9S mutant was higher than that induced by SG9R, it also induced high titres of circulating IgG, which gives the positive result with whole blood agglutination test. For this reason it was not studied in any depth.
The master strain SG9R was lyophilised in March 1955 and has been used on a number of occasions by Smith and other colleagues in the UK and elsewhere (Smith, 1969). It was lyophilised again by Smith in August 1955. This is the culture which has been used more recently by Paul Barrow in Smith’s laboratory since 1981 and who inherited Smith’s bacterial strain collection in 1987.
In 1991 Dr. Li Barber joined Smith laboratory as PhD student and whose work were closed related on developing SG9R and gene deletion mutants vaccine to prevent Salmonella enteritidis as well as Salmonella serological ELISA diagnosis kit which WHO recommended to be used in infected flocks ( references: WHO ‘ Guideline on detection and monitoring of salmonella infected flocks with particularly reference to salmonella enteritidis – report of a WHO consultation on Strategies for detection and monitoring of salmonella infected poultry flocks, Graz, Austria, 11-15 April 1994). This scientific work has lead to commercialised ELISA kit and currently this kit is marketed by Guildhay UK Ltd.