Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Patent
1993-09-20
1997-03-11
Campell, Bruce R.
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
4352523, 4353201, 435885, 435975, 536 231, 536 237, 536 2432, 935 9, C12Q 168, C07H 2104
Patent
active
056100116
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention is in the field of veterinary and human preventive medicine, in particular that of the diagnosis of and protection against infection by pathogenic strains of the bacterium Streptococcus suis.
Infections with Streptococcus suis serotype 2 in young pigs at about the time of weaning have been a growing problem in the Netherlands since 1983. The disease is characterised by meningitis, arthritis, sepsis and death (Clifton-Hadley 1983, ref. 6; Vecht et al. 1985, ref. 44; Windsor 1977, ref. 50). It is estimated that 5-10 per cent of farms have problems of this type. The mortality is estimated at 2.5% and the morbidity in affected farms is on average 2-5%. Therapeutic and preventive measures have only a limited effect. The economic damage is accordingly appreciable. The disease is a zoonosis. Humans are also susceptible to this infection, with the risk of sepsis and meningitis with possibly permanent side-effects; rare cases of death have been reported (Arends and Zanen 1988, ref. 2). This related mostly to cases of people with a skin wound coming into contact with infected pork. In particular, pig farmers and slaughterhouse staff belong to the risk group.
There are indications that the increased rate of illness on pig farms in the Netherlands since 1983 is to be ascribed to the import of breeding animals which are carriers of S. suis type 2. Carriers are often healthy adult pigs which harbour the streptococci in the tonsils and mucosa of the upper respiratory tract. The infection is transmitted via these carriers to susceptible animals, frequently piglets at weaning age. Diagnosis of animals which are already sick or have died is based on isolation and determination of S. suis type 2 from clinical samples or organs after necropsy. Detection of carriers is based on bacteriological examination of nose or throat swabs or tonsil biopsies using a selective/elective medium (Van Leengoed et al. 1987, ref. 27). On the basis of diagnostic testing to detect carriers, it should be possible to set up a control programme. However, testing for carriers using the conventional becteriological techniques is time-consuming, which complicates the processing of large numbers of samples; there is also a risk of false negative results due to overgrowth with contaminants. Finally, interpretation of the test demands a great deal of experience. Moreover, diagnosis and possible control on the basis of diagnosis are further complicated by the occurrence of differences in pathogenicity within the S. suis type 2 species. Regular testing for carriers within a control programme is sensible only if truly virulent strains of S. suis type 2 can be differentiated from avirulent strains. Current diagnostic techniques do not make such discrimination. Consequently, control based on the detection of carriers of virulent S. suis type 2 strains is not yet possible.
Differences in virulence are ascribed, inter alia, to the presence or absence of virulence factors. In 1984, Arends and Zanen (ref. 1) described "lysozyme-positive proteins" in human strains. In a study with experimental animals it was found that a "lysozyme-positive" strain (D-282) was pathogenic for gnotobiotic pigs, in contrast to a "lysozyme-negative" strain (T-15) (Vecht et al. 1989, ref. 43). The "lysozyme-positive protein " is probably identical to the muramidase-released protein (MRP) of strain D-282.
The pig industry in the Netherlands and many other countries has a pyramid structure, with a small number of breeding herds at the top, from where animals are distributed to replication herds. These supply a large number of fattening herds, supplying animal products to slaughterhouses. A control program based on diagnosis (certification of farms, elimination of positive carriers, import requirements) should primarily aim at creating herds which are free of S. suis type 2 high in this pyramid. A vaccine would primarily be useful in affecting herds lower in the pyramid. Furthermore, means and methods for diagnosing infections by Streptococcus suis in h
REFERENCES:
PL Felgner et al (1991) Science 349:351-352.
Watson et al (1987) Molecular Biology of the Gene 4th ed., p. 313.
Am. J. Vet. Res., vol. 50, No. 7, Jul. 1989, U. Vecht et al., pp. 1037-1043.
Abstracts of Papers, part I, 200th ACS National Meeting, Washington DC, 26-31 Aug. 1990, American Chemical Society, J. R. Lowe et al abstract No. 158.
Biological Abstracts, vol. 89, 1990, (Philadelphia, PA, US), G.
Frankel et al. p. 635, abstract No. 72068, Mol. Microbiol. 3(12): 1729-1734. 1989, see abstract.
Disserattion Abstracts Int'l B, vol. 52, No. 1, Jul. 1991, J. D. Mogollon Galvis: p. 102, see abstract.
Infection and Immunity, vol. 59, No. 9, Sep. 1991, U. Vecht et al.: pp. 3156-3162.
Smith Hilda E.
Vecht Uri
Campell Bruce R.
Centraal Diergeneeskundig Instituut
LandOfFree
Virulence-encoding DNA sequences of Strepococcus suis and relate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Virulence-encoding DNA sequences of Strepococcus suis and relate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Virulence-encoding DNA sequences of Strepococcus suis and relate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-442405