CLINICAL RESEARCH NOTE SOME FACTORS INFLUENCING THE MICROTEST METHOD FOR NEUTRALIZING ANTIBODIES TO THE VIRUS OF INFECTIOUS BOVINE RHINOTRACHEITIS
C. iz Q. DAR*cm0 MicroTest plate' methods (1) which greatly aid virus diagnostic procedures have been adapted to test for neutralizing antibodies to infectious bovine rhinotracheitis (IBR) virus (2, 3, 4, 7, 8). The reproducibility of the test was established by conducting titrations with individual serum samples and by conducting titrations with cell cultures from different fetuses. The specificity of the test was determined by conducting tests in parallel with another bovine herpes virus unrelated to IBR virus. The effect of a variable dose of challenge virus in the serum neutralization test was also studied. The IBR virus used routinely was Strain 108, a field isolate received from Dr. G. Klavano of the Provincial Veterinary Laboratory, Edmonton. Strain 108 was chosen for the tests as it produced high titer stocks of virus in cultures of bovine kidney cells, in which it produced cytopathic effects of all cells in four to five days, and because it was isolated locally. Strain 108 was neutralized by IBR neutralizing bovine anti-serum supplied by the Animal Diseases Research Institute (Eastern) and fixed complement in the presence of this antiserum. Another bovine herpes virus, Strain DN-599 (5, 6) supplied by Dr. S. B. Mohanty, Department of Veterinary Science, University of Maryland, College Park, Maryland, was also used to check the specificity of the test. Strain DN-599, a herpes virus which is antigenically distinct from all other bovine herpes viruses, was isolated by Mohanty from a one and onehalf year old steer with signs of respiratory illness. Bovine sera submitted to this laboratory for diagnostic purposes were employed in these studies. The vaccination status of the animals providing some sera was not known (VSNK).
100 85
So _
aa
100TrC1050
so 60
a.
251rClD50
20
Vaceiaoted
l00TC1Oso
Unooccinoted
Neotrolluiag titer of 4 or greoteor osbuod to be * ve M.utrolisiug titer grtoter thon 4 osomd to be * so
FIGURE 1. Percent positive serum samples from 232 vaccinated and 396 unvaccinated cattle at different test sensitivities.
Cell suspensions were prepared by trypsinization of bovine fetal kidney (BFK) primary cell monolayers and suspending the cells in twice the amount of medium used for the monolayer. Growth medium (GM) was Eagle's MEM containing 10% fetal calf serum, penicillin 400 I.U./ml, streptomycin 400 ug/ml and Mycostatin2 1.6 ,ug/ml. Doubling dilutions of the test serum were made in GM with a lotus-type dilutor3 in a volume of 0.05 ml. Except where noted, 25 TCID50 of virus in 0.05 ml of GM was added to each well and the serum-virus mixtures were incubated for one hour at room temperature. At this time 0.1 ml of cell suspension containing 2 x 104 cells was added to each well. Tests were incubated at 37°C in 5% CO2 in air for five days and the cultures were then examined with an inverted microscope. A permanent record could be obtained by staining the plates with crystal violet (10) (Figure 2). The serum dilution is the proportion of serum in the final serum-virus mixture and does not include the cell suspension volume. The titer of the serum is the reciprocal of its dilution caus-
Animal Pathology Division, Health of Animals Branch, Canada Department of Agriculture, Animal Diseases Research Institute (Western), P.O. Box 640, Lethbridge, Alberta T1J 3Z4 lFalcon tissue culture multi-well plates, Becton, Dickinson & Co. Ltd., Clarkson, Ontario.
2E. R. Squibb & Sons, Inc., New York, N.Y. 3Cooke Engineering Co., Alexandria, Va. 59
CAN. VET. JOUR., vol. 16, no. 2, February, 1975
ctoIDSo
CANADIAN VETERINARY JOURNAL
14
0-0s1*
FiGuRE 2. Cell- cultures used for detecting neutralizing antibody to IBR in MicroTest plates were stained with crystal violet. The boxed-in area includes results with the positive (+) serum control, negative (-) serum control, virus control (VC) and uninfected cell control (CC). Neutralizing antibodies were absent in samples 12, 18, 19, 20, 21, 24 and 25 and were present in titers 1/20 to 1/160 in the other sera tested. In this plate sera were initially diluted 1/10 and were added to the first two wells before making dilutions and adding virus. The stained (dark) cells were those in which cells were not destroyed.
ing inhibition of 25 or 100 TCID504 units for BFK monolayers. In all the experiments described the reciprocal of the initial dilution used was 4 except in the tests illustrated in Figure 2, where the reciprocal of the initial dilution was 20. Fifty percent probability tests on paired lots of matched observations (9) were used to compare data where large number of zero differences were present and the data could not be regarded as normally dis-
agreement was 59%. The differences in mean titer were less than one dilution step with the exception of the titration of one sample which showed a difference of one dilution step. Comparison of these differences using the 50% probability test showed no significant differences. Thus the number of replications did not significantly influence the mean titers obtained and this justifies the use of unreplicated titrations in the other experiments described in tributed. this note. One hundred sera were used to determine Fifty sera (VSNK) were used to test the the consistency of the test. Forty of the sera reproducibility of the system with secondary were negative in all tests. When these are in- BFK cells prepared the same day from difcluded agreement between single and dupli- ferent fetuses. There were no differences becate titrations was 84% and between single tween the results obtained with cells from titrations and titrations in quadruplicate the four fetuses (x2, 0-1.11JNS). Virus neutralization titers on 36 sera (VSNK) 4Titrations were made of the stock virus in sex- differed significantly (t = 4.52*) 5 with a tuplet and the number of TCID5 (amount of low correlation coefficient (0.20) when strains virus that will cause a cytopathic elect in 50% of DN-599 and 108 were compared and showed cultures inoculated) were calculated using the no significant difference (t = 1.886N5) and a Karber formula. Aliquots of 0.5 ml stock virus were placed in sterile 1 ml sealable vials (#223682) Wheaton Glass Co., MiUville, New Jersey and 5Level of significance 0.001 *0 0.01 stored at -80'C. The virus titer was determined * 0.05 in each test; the titer was unchanged for more than a year under these conditions. NS Not significant 60
IBR
high correlation (0.96) when two lots of stock virus strain 108 were compared. That some sera had antibodies to DN-599 is of interest, since antibodies to this virus were not recognized in a small survey of cattle sera collected in Maryland (6). Sera from 628 vaccinated and unvaccinated animals, intended for export, were used to determine the influence of the dose of virus employed (25 TCID50 versus 100 TCID50) in the test on the number of positive cattle (Figure 1). For vaccinated cattle, 25 TCID50 is of significantly greater sensitivity in detecting the response to the virus than 100 TCID50 (76% positive versus 53% positive, x2 = 4.64*..). In fact, if a titer of 4 is positive the test becomes even more sensitive (90% positive versus 77% positive for 25 TCID50 and 100 TCID50 respectively, x2 = 25.3 * ). Slightly more reactors were found among unvaccinated animals if a titer of 4 was considered negative when 25 TCID50 were used instead of 100 TCID50 (12% positive versus 10% positive, x2 = 6.0*). If titers of 4 are considered positive instead of negative the percentage of positives is identical in both dosage levels in these unvaccinated cattle. Percentage of positives in both vaccinated and unvaccinated cattle were lower than those found in a recent survey (6) but 95% of these export cattle were less than one and one-half years old. To conclude, IBR virus neutralization tests made with the MicroTest procedure were found to be reproducible in replicate titrations with individual serum samples and with secondary BFK cell cultures from the same and from different fetuses. The test appears specific as there was no correlation with the results obtained using bovine herpes strain DN-599 which differs serologically from IBR. Cattle in this area may have antibodies to this latter herpes virus as well as to the virus of IBR as some sera inhibited its growth. Among vaccinated cattle 25 TCID50 detected signfificantly more reactors than 100 TCID50 dose of challenge virus. In the unvaccinated animals there were a few more reactors when a titer of 4 was considered negative and an identical number of reactors when a titer of 4 was considered positive. Summary The MicroTest procedure for assays of IBR virus neutralizing antibodies has been shown to be reliable and the results are reproducible with secondary BFK cells from different fetuses. There was no correlation between the neutralizing antibody titers to IBR virus and 61
bovine herpes virus DN-599. Among vaccinated cattle 25 TCID50 detected significantly more reactors than 100 TCID50 dose of challenge virus; in the unvaccinated animals there were a few more reactors when a titer of 4 was considered negative and an identical number of reactors when a titer of 4 was considered positive. Resume
L'auteur a demontre l'efficacite de la microtechnique pour la recherche d'anticorps neutralisant le virus de la rhino-tracheite infectieuse bovine. II a egalement verifie la possibilite d'en reproduire les resultats en utilisant des cellules secondaires renales de differents foetus bovins. II ne decela pas de reciprocite entre les titres d'anticorps neutralisant le virus de la rhino-trach6ite infectieuse bovine et le virus herpes bovin DN-599. II obtint un plus grand nombre de reacteurs chez les sujets vaccines, lorsqu'il utilisait 25 doses infectantes 50 de virus en culture tissulaire que lorsqu'il en employait 100. En considerant comme negatif un titre de 1:4, il decela quelques reacteurs de plus chez les sujets non vaccines; par ailleurs, le nombre de reacteurs s'avera identique lorsqu'il considerait ce titre de 1:4 comme positif. Acknowledgments My thanks are due to Dr. S. E. Magwood, Director of this Institute for help in preparing this manuscript; to G. C. Kozub and N. Kloppenborg of Canada Agriculture Research Station, Lethbridge, for assistance with statistics and for Figure 2 respectively and to Siv Smithson, Donna Harker and Norma Dow for technical assistance. References 1. ASHCROFT, J., G. S. PLATT, and B. J. MAinMENT. The accuracy of the microtiter technique. Med. Lab. Tech. 28: 129-132. 1971. 2. BLACK, J. W. Use of the microtiter serum neutralization test for the diagnosis of IBR, BVD and other bovine and porcine viral diseases. Proc. 74th. a. Meet. U.S. Anim. Hlth Ass. pp. 515-521. 1971. 3. DARCEL, C. LE Q. The prevalence of neutralizing antibodies to infectious bovine rhinotracheitis (IBR) in cattle in Alberta. Can. vet. J. 14: 167-168. 1973. 4. MCKERCHER, D. G. Microtiter serum neutralization for infectious bovine rhinotracheitis. In "Recommended laboratory techniques for diagnosing infectious bovine rhinotracheitis, bovine diarrhea and shipping fever (parainfluenza-3)". Committee for Recommended Standard Technique for Diagnosing Bovine Respiratory Disease. Ann. Meet. Amer. Ass. Vet. Lab. Diag. Suppl. 1. 1971.
CANADLAN VETERINARY JOURNAL
5. MOHANTY, S. B., R. D. HAMMOND and M. G. LILLIE. A new bovine herpes virus and its effect on experimentally infected calves. Arch. ges. Virusforsch. 33: 394-395. 1971. 6. MOHANTY, S. B. New herpes viral and rhinoviral respiratory infections. J. Am. vet. med. Ass. 163: 855-857. 1973. 7. Rossi, C. R. and G. K. KIESEL, Microtiter tests for detecting antibody in bovine serum to parainfluenza-3 virus, infectious bovine rhinotracheitis virus and bovine virus diarrhea virus. Appl. Microbiol. 22: 32-36. 1971.
PRIX
8. SAUNDERS, J. R., W. A. WETZSTEIN, and M. G.
PRIOR. Infectious bovine rhinotracheitis (IBR): Serum antibodies in cattle in Saskatchewan. Can. vet. J. 13: 240-241. 1972. 9. STEEL, R. G. D. and J. H. ToRRIE. Principles and procedures of Statistics. McGrawHill. 1960. 10. WITTE, K. L. Micro-color test for assay of transmissible gastroenteritis virus-neutralizing antibodies. Arch. ges. Virusforsch. 33: 171176. 1971.
ViTERINAIRE
Dans le but d'encourager le progres en m6decine et en chirurgie des petits animaux, la compagnie General Foods Limited, par l'entremise du Centre de Services professionnels Gaines, a institu6 le "prix vet6rinaire Gaines". Ce prix sera d6cerne annuellement a un veterinaire dont on aura jug6 que le travail a contribue eminemment a l'avancement de la m6decine et de la chirurgie des petits animaux, soit en recherches cliniques ou soit en recherches fondamentales. La pr6sentation de rceuvre a 6valuer devra avoir fait l'objet d'une publication dans des revues vet6rinaires d'envergure ou d'une communication a des congres professionnels. On consid6rera en premier lieu les travaux ex6cutes au cours des cinq dernieres ann6es, bien que, en second lieu, on puisse aussi appr6cier les oeuvres anterieures a cette p6riode pour des membres qui demeurent toujours actifs.
GAINES
Toute personne peut, jusqu'au 31 mars 1975 au plus tard, pr6senter des candidats pour le prix de 1975 en s'adressant au Comite executif de rACV. Avec chaque recommandation, le proposeur devra soumettre une description des travaux de son candidat. II devra aussi demontrer comment ces travaux ont contribue a ravancement de la medecine et de la chirurgie des petits animaux et soumettre une bibliographie pertinente (s'il en existe) en meme temps qu'une notice biographique. Le prix consistera en un medaillon d'or accompagnant une somme de $500.00. Le tout sera decern6 a l'occasion du congres annuel. Toute correspondance a ce sujet peut etre adressee au soussigne. J. R. Kinney Secretaire executif 360 avenue Bronson Ottawa, Ontario K1R 6J3
ABSTRACT Levels of terminal pesticide residues in domestic meat - a cross country survey. P. W. Saschenbrecker and F. Tittiger (An. Path. Lab., H of A., Agr. Canada, Guelph, Ontario).
ably to products of some foreign countries. DDT and metabolites are still found at levels above 0.01 ppm, exhibiting a gradually decreasing trend. Newer pesticides used as substitutes have not reached proportions to cause concern. PCB compounds show marginal inA total of 2237 samples of beef, mutton, creases in both incidences and levels over the pork, and fowl tissue obtained from Canadian past three years. meat packing establishments throughout the country were analyzed for a wide scope of Research Rostrum of the Twenty-sixth Canaagricultural pesticides and some industrial dian Veterinary Medical Association Annual pollutants. Canadian meats compare favor- Convention, Guelph, Ontario 1974. A2
C. iz Q. DAR*cm0 MicroTest plate' methods (1) which greatly aid virus diagnostic procedures have been adapted to test for neutralizing antibodies to infectious bovine rhinotracheitis (IBR) virus (2, 3, 4, 7, 8). The reproducibility of the test was established by conducting titrations with individual serum samples and by conducting titrations with cell cultures from different fetuses. The specificity of the test was determined by conducting tests in parallel with another bovine herpes virus unrelated to IBR virus. The effect of a variable dose of challenge virus in the serum neutralization test was also studied. The IBR virus used routinely was Strain 108, a field isolate received from Dr. G. Klavano of the Provincial Veterinary Laboratory, Edmonton. Strain 108 was chosen for the tests as it produced high titer stocks of virus in cultures of bovine kidney cells, in which it produced cytopathic effects of all cells in four to five days, and because it was isolated locally. Strain 108 was neutralized by IBR neutralizing bovine anti-serum supplied by the Animal Diseases Research Institute (Eastern) and fixed complement in the presence of this antiserum. Another bovine herpes virus, Strain DN-599 (5, 6) supplied by Dr. S. B. Mohanty, Department of Veterinary Science, University of Maryland, College Park, Maryland, was also used to check the specificity of the test. Strain DN-599, a herpes virus which is antigenically distinct from all other bovine herpes viruses, was isolated by Mohanty from a one and onehalf year old steer with signs of respiratory illness. Bovine sera submitted to this laboratory for diagnostic purposes were employed in these studies. The vaccination status of the animals providing some sera was not known (VSNK).
100 85
So _
aa
100TrC1050
so 60
a.
251rClD50
20
Vaceiaoted
l00TC1Oso
Unooccinoted
Neotrolluiag titer of 4 or greoteor osbuod to be * ve M.utrolisiug titer grtoter thon 4 osomd to be * so
FIGURE 1. Percent positive serum samples from 232 vaccinated and 396 unvaccinated cattle at different test sensitivities.
Cell suspensions were prepared by trypsinization of bovine fetal kidney (BFK) primary cell monolayers and suspending the cells in twice the amount of medium used for the monolayer. Growth medium (GM) was Eagle's MEM containing 10% fetal calf serum, penicillin 400 I.U./ml, streptomycin 400 ug/ml and Mycostatin2 1.6 ,ug/ml. Doubling dilutions of the test serum were made in GM with a lotus-type dilutor3 in a volume of 0.05 ml. Except where noted, 25 TCID50 of virus in 0.05 ml of GM was added to each well and the serum-virus mixtures were incubated for one hour at room temperature. At this time 0.1 ml of cell suspension containing 2 x 104 cells was added to each well. Tests were incubated at 37°C in 5% CO2 in air for five days and the cultures were then examined with an inverted microscope. A permanent record could be obtained by staining the plates with crystal violet (10) (Figure 2). The serum dilution is the proportion of serum in the final serum-virus mixture and does not include the cell suspension volume. The titer of the serum is the reciprocal of its dilution caus-
Animal Pathology Division, Health of Animals Branch, Canada Department of Agriculture, Animal Diseases Research Institute (Western), P.O. Box 640, Lethbridge, Alberta T1J 3Z4 lFalcon tissue culture multi-well plates, Becton, Dickinson & Co. Ltd., Clarkson, Ontario.
2E. R. Squibb & Sons, Inc., New York, N.Y. 3Cooke Engineering Co., Alexandria, Va. 59
CAN. VET. JOUR., vol. 16, no. 2, February, 1975
ctoIDSo
CANADIAN VETERINARY JOURNAL
14
0-0s1*
FiGuRE 2. Cell- cultures used for detecting neutralizing antibody to IBR in MicroTest plates were stained with crystal violet. The boxed-in area includes results with the positive (+) serum control, negative (-) serum control, virus control (VC) and uninfected cell control (CC). Neutralizing antibodies were absent in samples 12, 18, 19, 20, 21, 24 and 25 and were present in titers 1/20 to 1/160 in the other sera tested. In this plate sera were initially diluted 1/10 and were added to the first two wells before making dilutions and adding virus. The stained (dark) cells were those in which cells were not destroyed.
ing inhibition of 25 or 100 TCID504 units for BFK monolayers. In all the experiments described the reciprocal of the initial dilution used was 4 except in the tests illustrated in Figure 2, where the reciprocal of the initial dilution was 20. Fifty percent probability tests on paired lots of matched observations (9) were used to compare data where large number of zero differences were present and the data could not be regarded as normally dis-
agreement was 59%. The differences in mean titer were less than one dilution step with the exception of the titration of one sample which showed a difference of one dilution step. Comparison of these differences using the 50% probability test showed no significant differences. Thus the number of replications did not significantly influence the mean titers obtained and this justifies the use of unreplicated titrations in the other experiments described in tributed. this note. One hundred sera were used to determine Fifty sera (VSNK) were used to test the the consistency of the test. Forty of the sera reproducibility of the system with secondary were negative in all tests. When these are in- BFK cells prepared the same day from difcluded agreement between single and dupli- ferent fetuses. There were no differences becate titrations was 84% and between single tween the results obtained with cells from titrations and titrations in quadruplicate the four fetuses (x2, 0-1.11JNS). Virus neutralization titers on 36 sera (VSNK) 4Titrations were made of the stock virus in sex- differed significantly (t = 4.52*) 5 with a tuplet and the number of TCID5 (amount of low correlation coefficient (0.20) when strains virus that will cause a cytopathic elect in 50% of DN-599 and 108 were compared and showed cultures inoculated) were calculated using the no significant difference (t = 1.886N5) and a Karber formula. Aliquots of 0.5 ml stock virus were placed in sterile 1 ml sealable vials (#223682) Wheaton Glass Co., MiUville, New Jersey and 5Level of significance 0.001 *0 0.01 stored at -80'C. The virus titer was determined * 0.05 in each test; the titer was unchanged for more than a year under these conditions. NS Not significant 60
IBR
high correlation (0.96) when two lots of stock virus strain 108 were compared. That some sera had antibodies to DN-599 is of interest, since antibodies to this virus were not recognized in a small survey of cattle sera collected in Maryland (6). Sera from 628 vaccinated and unvaccinated animals, intended for export, were used to determine the influence of the dose of virus employed (25 TCID50 versus 100 TCID50) in the test on the number of positive cattle (Figure 1). For vaccinated cattle, 25 TCID50 is of significantly greater sensitivity in detecting the response to the virus than 100 TCID50 (76% positive versus 53% positive, x2 = 4.64*..). In fact, if a titer of 4 is positive the test becomes even more sensitive (90% positive versus 77% positive for 25 TCID50 and 100 TCID50 respectively, x2 = 25.3 * ). Slightly more reactors were found among unvaccinated animals if a titer of 4 was considered negative when 25 TCID50 were used instead of 100 TCID50 (12% positive versus 10% positive, x2 = 6.0*). If titers of 4 are considered positive instead of negative the percentage of positives is identical in both dosage levels in these unvaccinated cattle. Percentage of positives in both vaccinated and unvaccinated cattle were lower than those found in a recent survey (6) but 95% of these export cattle were less than one and one-half years old. To conclude, IBR virus neutralization tests made with the MicroTest procedure were found to be reproducible in replicate titrations with individual serum samples and with secondary BFK cell cultures from the same and from different fetuses. The test appears specific as there was no correlation with the results obtained using bovine herpes strain DN-599 which differs serologically from IBR. Cattle in this area may have antibodies to this latter herpes virus as well as to the virus of IBR as some sera inhibited its growth. Among vaccinated cattle 25 TCID50 detected signfificantly more reactors than 100 TCID50 dose of challenge virus. In the unvaccinated animals there were a few more reactors when a titer of 4 was considered negative and an identical number of reactors when a titer of 4 was considered positive. Summary The MicroTest procedure for assays of IBR virus neutralizing antibodies has been shown to be reliable and the results are reproducible with secondary BFK cells from different fetuses. There was no correlation between the neutralizing antibody titers to IBR virus and 61
bovine herpes virus DN-599. Among vaccinated cattle 25 TCID50 detected significantly more reactors than 100 TCID50 dose of challenge virus; in the unvaccinated animals there were a few more reactors when a titer of 4 was considered negative and an identical number of reactors when a titer of 4 was considered positive. Resume
L'auteur a demontre l'efficacite de la microtechnique pour la recherche d'anticorps neutralisant le virus de la rhino-tracheite infectieuse bovine. II a egalement verifie la possibilite d'en reproduire les resultats en utilisant des cellules secondaires renales de differents foetus bovins. II ne decela pas de reciprocite entre les titres d'anticorps neutralisant le virus de la rhino-trach6ite infectieuse bovine et le virus herpes bovin DN-599. II obtint un plus grand nombre de reacteurs chez les sujets vaccines, lorsqu'il utilisait 25 doses infectantes 50 de virus en culture tissulaire que lorsqu'il en employait 100. En considerant comme negatif un titre de 1:4, il decela quelques reacteurs de plus chez les sujets non vaccines; par ailleurs, le nombre de reacteurs s'avera identique lorsqu'il considerait ce titre de 1:4 comme positif. Acknowledgments My thanks are due to Dr. S. E. Magwood, Director of this Institute for help in preparing this manuscript; to G. C. Kozub and N. Kloppenborg of Canada Agriculture Research Station, Lethbridge, for assistance with statistics and for Figure 2 respectively and to Siv Smithson, Donna Harker and Norma Dow for technical assistance. References 1. ASHCROFT, J., G. S. PLATT, and B. J. MAinMENT. The accuracy of the microtiter technique. Med. Lab. Tech. 28: 129-132. 1971. 2. BLACK, J. W. Use of the microtiter serum neutralization test for the diagnosis of IBR, BVD and other bovine and porcine viral diseases. Proc. 74th. a. Meet. U.S. Anim. Hlth Ass. pp. 515-521. 1971. 3. DARCEL, C. LE Q. The prevalence of neutralizing antibodies to infectious bovine rhinotracheitis (IBR) in cattle in Alberta. Can. vet. J. 14: 167-168. 1973. 4. MCKERCHER, D. G. Microtiter serum neutralization for infectious bovine rhinotracheitis. In "Recommended laboratory techniques for diagnosing infectious bovine rhinotracheitis, bovine diarrhea and shipping fever (parainfluenza-3)". Committee for Recommended Standard Technique for Diagnosing Bovine Respiratory Disease. Ann. Meet. Amer. Ass. Vet. Lab. Diag. Suppl. 1. 1971.
CANADLAN VETERINARY JOURNAL
5. MOHANTY, S. B., R. D. HAMMOND and M. G. LILLIE. A new bovine herpes virus and its effect on experimentally infected calves. Arch. ges. Virusforsch. 33: 394-395. 1971. 6. MOHANTY, S. B. New herpes viral and rhinoviral respiratory infections. J. Am. vet. med. Ass. 163: 855-857. 1973. 7. Rossi, C. R. and G. K. KIESEL, Microtiter tests for detecting antibody in bovine serum to parainfluenza-3 virus, infectious bovine rhinotracheitis virus and bovine virus diarrhea virus. Appl. Microbiol. 22: 32-36. 1971.
PRIX
8. SAUNDERS, J. R., W. A. WETZSTEIN, and M. G.
PRIOR. Infectious bovine rhinotracheitis (IBR): Serum antibodies in cattle in Saskatchewan. Can. vet. J. 13: 240-241. 1972. 9. STEEL, R. G. D. and J. H. ToRRIE. Principles and procedures of Statistics. McGrawHill. 1960. 10. WITTE, K. L. Micro-color test for assay of transmissible gastroenteritis virus-neutralizing antibodies. Arch. ges. Virusforsch. 33: 171176. 1971.
ViTERINAIRE
Dans le but d'encourager le progres en m6decine et en chirurgie des petits animaux, la compagnie General Foods Limited, par l'entremise du Centre de Services professionnels Gaines, a institu6 le "prix vet6rinaire Gaines". Ce prix sera d6cerne annuellement a un veterinaire dont on aura jug6 que le travail a contribue eminemment a l'avancement de la m6decine et de la chirurgie des petits animaux, soit en recherches cliniques ou soit en recherches fondamentales. La pr6sentation de rceuvre a 6valuer devra avoir fait l'objet d'une publication dans des revues vet6rinaires d'envergure ou d'une communication a des congres professionnels. On consid6rera en premier lieu les travaux ex6cutes au cours des cinq dernieres ann6es, bien que, en second lieu, on puisse aussi appr6cier les oeuvres anterieures a cette p6riode pour des membres qui demeurent toujours actifs.
GAINES
Toute personne peut, jusqu'au 31 mars 1975 au plus tard, pr6senter des candidats pour le prix de 1975 en s'adressant au Comite executif de rACV. Avec chaque recommandation, le proposeur devra soumettre une description des travaux de son candidat. II devra aussi demontrer comment ces travaux ont contribue a ravancement de la medecine et de la chirurgie des petits animaux et soumettre une bibliographie pertinente (s'il en existe) en meme temps qu'une notice biographique. Le prix consistera en un medaillon d'or accompagnant une somme de $500.00. Le tout sera decern6 a l'occasion du congres annuel. Toute correspondance a ce sujet peut etre adressee au soussigne. J. R. Kinney Secretaire executif 360 avenue Bronson Ottawa, Ontario K1R 6J3
ABSTRACT Levels of terminal pesticide residues in domestic meat - a cross country survey. P. W. Saschenbrecker and F. Tittiger (An. Path. Lab., H of A., Agr. Canada, Guelph, Ontario).
ably to products of some foreign countries. DDT and metabolites are still found at levels above 0.01 ppm, exhibiting a gradually decreasing trend. Newer pesticides used as substitutes have not reached proportions to cause concern. PCB compounds show marginal inA total of 2237 samples of beef, mutton, creases in both incidences and levels over the pork, and fowl tissue obtained from Canadian past three years. meat packing establishments throughout the country were analyzed for a wide scope of Research Rostrum of the Twenty-sixth Canaagricultural pesticides and some industrial dian Veterinary Medical Association Annual pollutants. Canadian meats compare favor- Convention, Guelph, Ontario 1974. A2
