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105. Development of an ELISA for the differential serological diagnosis of pestivirus infections in pigs
Room
B: 16.45-17.00
103. Restoration of sensitivity to anticoccidial ionophores in Eimeria populations following use of live coccidiosis vaccines in broiler chickens CHAPMAN,
Department
of Poultry
Science,
H.D.,**
Universit?,
MCFARLAND,
ofArkansas,
Ionophores such as salinomycin (SAL) are widely used for the control of coccidiosis in broiler chickens but evidence has been obtained that they are not as effective as when first introduced. It has been proposed that the use of vaccines comprising drug-sensitive strains of Eimeriu (Coccivac@, Paracox@) could repopulate broiler houses with these strains and that, if vaccination is followed by ionophore use, the efficacy of the latter would be improved. Evidence to support this has now been obtained. The efficacy of SAL against isolates of Eimeria obtained from pens following four successive flocks given SAL or four flocks
J.L.
Fayetteville,
AR, 72701, USA
vaccinated with Coccivac-B@ has been measured by comparing oocysts produced by medicated birds with that of infected non-medicated controls. Oocyst production of isolates following medication with SAL was 38% of controls indicating that they were partially resistant to the drug whereas oocyst production of isolates following vaccination was 5% of the controls indicating that sensitivity to SAL had been restored. It is suggested that alternation of the use of drugs and vaccines may be a means to ameliorate the problem of drug resistance and could contribute to the successml long-term control of coccidiosis.
Room C. Theme: Virology Room
C:
10.15-10.30 104. The practical significance of the different pestivirus genotypes in British cattle and sheep NETTLETON,
‘Moredun
P.F.,‘*
MALEY,
M.,’
ALEXANDER,
K.,’
GILRAY,
Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Mdlothian, EH26 Division, Inverness, IV2 452; 3University of Veterinary Medicine, Komenskeho
In cattle, two genotypes of bovine virus diarrhoea virus (BVDV) are recognised. BVDV-1 has been known for many years and is widespread in cattle throughout the world, while BVDV-2 was only identified in the 1990’s in North America and sporadically elsewhere, most recently in Britain. Isolates of both genotypes can cause a wide range of clinical diseases with certain strains of BVDV-2 being associated with a severe acute haemorrhagic syndrome. BVDV-1 can be divided into at least 11 phylogenetic groups. Genotyping of 146 recent Scottish isolates of BVDV from a wide variety of clinical syndromes has shown that they were all BVDV-1 with 143 being BVDV-la and 3 BVDV-lb. Sequencing of
J.,’ GUNN,
G.,2 VILCEK,
S3
OPZ; 2Scottish Agricultural College Veterinary 73, SK-041 81 Kosice, Slovak Republic
Science
PCR-products from selected isolates showed them to be closely related to other British and USA BVDV-1 strains. Among British sheep it is now believed that two pestivirus genotypes are circulating, namely border disease virus (BDV) and BVDV-1. Approximately 60% of isolates are BDV while 40% are BVDV-1 suggesting that pestiviruses from cattle frequently infect sheep. Phylogenetics is a very useful tool for classifying pestiviruses and tracing the origins of new viruses. The practical significance of the different pestivirus genotypes in British cattle and sheep will be discussed in terms of diagnosis, control including vaccination and epidemiology.
Room C: 10.30-10.45 105. Development of an ELISA for the differential serological diagnosis of pestivirus infections in pigs MOORE,
&ology
Department,
Veterinary
S.J.,**
Laboratories
ASFOR,
A.. SANDVIK,
Agency-~ Wqvhridge,
Classical swine fever (CSF) virus, along with bovine viral diarrhoea virus types 1 and 2, and border disease virus are members of the Pestivirus genus of the family Flaviviridae. All four viruses infect pigs, can cause similar disease and also induction of antibodies that crossreact with the other pestiviruses. CSF is an OIE List A disease, and exotic to the UK. It is, therefore, essential that serological tests are able to discriminate between infection of pigs with classical swine fever virus and the other, endemic, pestiviruses. The use of virus specific
T., WAKELEY,
Woodham
P.R.
Lane, New Haw, Addlestone,
Surrey,
KTI5
3NB
monoclonal antibodies can overcome the problem of cross-reactions. In surveillance for CSF, an ELISA which could test a sample for antibodies to all four pestiviruses would be useful, being much more rapid than the differential virus neutralisation tests currently used. We will describe the production and purification of recombinant E2 glycoproteins in insect cells, the selection of a panel of virus specific anti-E2 glycoprotein monoclonal antibodies and the strategies used to develop a differential ELISA for pig pestivirus serology.
B: 16.45-17.00
103. Restoration of sensitivity to anticoccidial ionophores in Eimeria populations following use of live coccidiosis vaccines in broiler chickens CHAPMAN,
Department
of Poultry
Science,
H.D.,**
Universit?,
MCFARLAND,
ofArkansas,
Ionophores such as salinomycin (SAL) are widely used for the control of coccidiosis in broiler chickens but evidence has been obtained that they are not as effective as when first introduced. It has been proposed that the use of vaccines comprising drug-sensitive strains of Eimeriu (Coccivac@, Paracox@) could repopulate broiler houses with these strains and that, if vaccination is followed by ionophore use, the efficacy of the latter would be improved. Evidence to support this has now been obtained. The efficacy of SAL against isolates of Eimeria obtained from pens following four successive flocks given SAL or four flocks
J.L.
Fayetteville,
AR, 72701, USA
vaccinated with Coccivac-B@ has been measured by comparing oocysts produced by medicated birds with that of infected non-medicated controls. Oocyst production of isolates following medication with SAL was 38% of controls indicating that they were partially resistant to the drug whereas oocyst production of isolates following vaccination was 5% of the controls indicating that sensitivity to SAL had been restored. It is suggested that alternation of the use of drugs and vaccines may be a means to ameliorate the problem of drug resistance and could contribute to the successml long-term control of coccidiosis.
Room C. Theme: Virology Room
C:
10.15-10.30 104. The practical significance of the different pestivirus genotypes in British cattle and sheep NETTLETON,
‘Moredun
P.F.,‘*
MALEY,
M.,’
ALEXANDER,
K.,’
GILRAY,
Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Mdlothian, EH26 Division, Inverness, IV2 452; 3University of Veterinary Medicine, Komenskeho
In cattle, two genotypes of bovine virus diarrhoea virus (BVDV) are recognised. BVDV-1 has been known for many years and is widespread in cattle throughout the world, while BVDV-2 was only identified in the 1990’s in North America and sporadically elsewhere, most recently in Britain. Isolates of both genotypes can cause a wide range of clinical diseases with certain strains of BVDV-2 being associated with a severe acute haemorrhagic syndrome. BVDV-1 can be divided into at least 11 phylogenetic groups. Genotyping of 146 recent Scottish isolates of BVDV from a wide variety of clinical syndromes has shown that they were all BVDV-1 with 143 being BVDV-la and 3 BVDV-lb. Sequencing of
J.,’ GUNN,
G.,2 VILCEK,
S3
OPZ; 2Scottish Agricultural College Veterinary 73, SK-041 81 Kosice, Slovak Republic
Science
PCR-products from selected isolates showed them to be closely related to other British and USA BVDV-1 strains. Among British sheep it is now believed that two pestivirus genotypes are circulating, namely border disease virus (BDV) and BVDV-1. Approximately 60% of isolates are BDV while 40% are BVDV-1 suggesting that pestiviruses from cattle frequently infect sheep. Phylogenetics is a very useful tool for classifying pestiviruses and tracing the origins of new viruses. The practical significance of the different pestivirus genotypes in British cattle and sheep will be discussed in terms of diagnosis, control including vaccination and epidemiology.
Room C: 10.30-10.45 105. Development of an ELISA for the differential serological diagnosis of pestivirus infections in pigs MOORE,
&ology
Department,
Veterinary
S.J.,**
Laboratories
ASFOR,
A.. SANDVIK,
Agency-~ Wqvhridge,
Classical swine fever (CSF) virus, along with bovine viral diarrhoea virus types 1 and 2, and border disease virus are members of the Pestivirus genus of the family Flaviviridae. All four viruses infect pigs, can cause similar disease and also induction of antibodies that crossreact with the other pestiviruses. CSF is an OIE List A disease, and exotic to the UK. It is, therefore, essential that serological tests are able to discriminate between infection of pigs with classical swine fever virus and the other, endemic, pestiviruses. The use of virus specific
T., WAKELEY,
Woodham
P.R.
Lane, New Haw, Addlestone,
Surrey,
KTI5
3NB
monoclonal antibodies can overcome the problem of cross-reactions. In surveillance for CSF, an ELISA which could test a sample for antibodies to all four pestiviruses would be useful, being much more rapid than the differential virus neutralisation tests currently used. We will describe the production and purification of recombinant E2 glycoproteins in insect cells, the selection of a panel of virus specific anti-E2 glycoprotein monoclonal antibodies and the strategies used to develop a differential ELISA for pig pestivirus serology.