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A Study of the Behavior of Six Infectious Bronchitis Virus Strains in Chicken Embryos
346
ISAACKS, REID, DAVIES, QUISENBEERY AND COUCH
Singsen, E. P., 1955. Feeding and management systems for growing pullets and their effect on adult performance. Abstracts of papers, Texas Nutrition Conf. p. 57. Stephenson, A. B., and R. L. Bryant, 1944. The value of sod range for starting chicks, growing pullets and laying hens. Virginia Agri. Expt. Sta. Bull. No. 362. Sunde, M. L., W. M. Cravens, H. R. Bird and J. G. Halpin, 1954. The effect of complete and incomplete growing diets ond subsequent performance of the laying hen. Poultry Sci. 33: 779-784. Winter, A. R., and K. F. Schlamb, 1948. Influence of range versus confinement rearing on growth feed consumption, egg production and livability. Poultry Sci. 27: 571-578.
A Study of the Behavior of Six Infectious Bronchitis Virus Strains in Chicken Embryos L. G. RAGGI AND R. G. RAYMOND*
School of Veterinary Medicine, University of California, Davis (Received for publication July 6, 1959)
HE RESPONSE of susceptible chickens to inoculation with some commercially available infectious bronchitis (IB) vaccines formed the subject of investigation of the first paper of this series (Raggi and Bankowski, 1956). The main objective of the present study was to investigate whether or not the pathogenicity of the above IB vaccine strains for chicken embryos was sufficiently characteristic for use as a criterion to differentiate a field strain from a vaccinal strain of IB. An attempt was also made to stabilize the time and the pattern of death of normal chicken embryos inoculated with one of the strains (No. 6) of infectious bronchitis virus (IBV).
T
* Present address: Heisdorf & Nelson Farms, Inc., Redmond, Washington.
MATERIALS AND PROCEDURE
IB vaccinal strains obtained directly from the manufacturers were stored at 2°C. for a few days before being tested. The vaccines were reconstituted by aspirating the diluent with a sterile syringe and needle inserted through the rubber stopper previously swabbed with 95 percent ethyl alcohol, and gently flamed. The diluent was introduced aseptically into the bottle containing the lyophilized vaccine. Each inoculum was tested for bacterial, PPLO (Adler et al., 1954) and Newcastle disease virus contamination, with negative results. Strain 6 was originally isolated from a field outbreak of IB by Dr. H. Van Roekel of the University of Massachusetts. The infected amnio-allantoic fluid (aafl) of the chicken embryo passage constituted the inoculum. This aafl was also chosen to study
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
Payne, L. F., and C. L. Gish, 1943. Grass and alfalfa as silage forage and meal for poultry. Kansas Agri. Expt. Sta. Bull. No. 320. Pepper, W. F., S. J. Slinger, H. L. Orr and E. S. Snyder, 1959. Effect of high and low energy diets and range versus confinement rearing on egg production and quality of fresh and held eggs. Poultry Sci. 38: 379-38S. Schneider, A. J., B. B. Bohren and V. L. Anderson, 1955. The effect of restricted feeding on several genetically controlled characters in the fowl. Poultry Sci. 34: 691-702. Singsen, E. P., L. D. Matterson, A. Kozeff and L. D. Stinson, 1954. The effects of feeding high and low efficiency rations to growing pullets on their subsequent laying performance. Poultry Sci. 33: 1081.
347
BRONCHITIS VIRUS STRAINS
(1) dwarfism and "curling"; (2) size; (3) presence of hemorrhages or other gross lesions; (4) length along the long axis. Dwarfism and curling were previously described (Beaudette and Hudson, 1937; Loomis et al., 1950; Fabricant, 1949) as changes observed in embryos infected with
IBV. Cutaneous hemorrhages are observed in embryos infected with Newcastle disease virus. Each strain was inoculated into 60 c.e.e. Twelve additional c.e.e. of the same source and age were used as normal controls. RESULTS
Table 1 indicates that, with the exception of strain 6, no mortality was experienced with any of the IBV strains in the first 48 hours after inoculation. Hemorrhages were not noticed in the dead embryos. The embryos inoculated with strain 1 appeared dwarfed and curled. The pathogenicity of this strain was further evidenced by a 70.5 percent mortality within ten days of observation. Strains 2 and 3 had similar effects. All the dead embryos examined from eggs inoculated with both strains appeared fully developed and no curling was noticeable. Strain 4 behaved similarly to strains 2 and 3, with the exception that a few of the dead embryos were undeveloped and curled. Strain 5 caused a total mortality of 52.0 percent. The majority of deaths (40 percent) occurred on the third and fourth day after inoculation. The greatest egg-killing power was mani-
TABLE 1.—Death pattern of six infectious bronchitis virus strains in embryos Percentage of eggs dead on a daily basis IBV strains 1* 2** 3** 4*** 5**** 6*
1
2
3
4
5
6
7
8
9
10
0 0 0 0 0 0
0 0 0 0 0 6
13 18.2 8.8 4.4 26 10
13.3 15.9 4.4 11.1 14 14
8.8 13.6 4.4 11.1 2 16
11.1 2.3 6.6 8.8 0 28
2.2 2.3 2.2 2.2 10 10
4.4 4.6 0 0 0 10
6.6 0 0 0 0
11.1 2.3 17.7 20.0 0
Total percentage of deaths 70.5 59.2 44.1 57.6 52.0 94.0
* Most of the dead embryos were found to be incompletely developed, and "curled"; maximal length was 50 mm. ** All of the dead embryos examined appeared to be fully developed and no curling was noticeable. When strains 2 and 3 were inoculated into chickens susceptible to IB, their immunogenicity was not satisfactory. *** Only a few of the dead embryos were undeveloped and curled. **** Dwarfism present in the majority of dead embryos.
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
the death pattern of chicken embryonating eggs (c.e.e.) through 17 serial passages. To eliminate as many variables as possible, the c.e.e. were obtained from one source. After incubation for nine days, the eggs were candled, and an area of the shell above the air cell swabbed with 95 percent alcohol, painted with 8 percent tincture of iodine, drilled, and painted again with iodine. To avoid cross-contamination of strains, one strain was tested at a time. Each egg was inoculated according to the method of Cunningham (1948) with 0.2 ml. of the reconstituted vaccine or undiluted aafi. The holes were sealed with Duco cement and the eggs incubated at 35.5°C. Previous trials indicated that this temperature was most favorable for growth of IB virus. The eggs were candled three times a day. Embryos that died on or before the tenth day of incubation were opened and examined for:
348
L. G. RAGGI AND R. G. RAYMOND
Of the six strains studied, strain 1 appeared to predominate in producing curling, which was observed in 30.S percent of the embryos, with two cases of schistosomas; 70.5 percent of the embryos were dead within ten days following inoculation. Death pattern oj c.e.e. inoculated with strain 6. Strain 6 was chosen to study the death pattern in embryos. Fig. 1 indicates that 17 serial passages of the aafl of freshly dead embryos did not result in a constant and reproducible death pattern. Eggs of the sixth passage, inoculated with aafl of an embryo that died on the 48th hour following inoculation, all died at approximately the 48th hour, but the successive passages clearly showed an irregularity of the death curve. Possible changes in pathogenicity, or possible adaptation of the virus to embryonic tissue with a loss of pathogenicity for growing birds, were tested by inoculation of susceptible birds with aafl of the 9th and 13 th serial passages, respectively. Two IB immune birds were also inoculated intratracheally and intramuscularly to detect, if present, contamination with other pathogenic viruses of chickens. Characteristic and typical IB signs of comparable severity were observed within 24-48 hours in birds inoculated with both the 9th and the 13th
PASSAGE 1
: -
A
LL..
PASSAGE 7
:
PASSAGE 6
PASSAGE 2
;.d PASSAGE 4
,A... PASSAGE 14
.
PASSAGE 9
PASSAGE 15 .
PASSAGE 10
PASSAGE 16 „
\,Ax,.:
A/\... PASSAGE II
PASSAGE 5
: PASSAGE 6
PASSAGE 13 -
PASSAGE 17 _
..A^.."7\A...'
:
PASSAGE 12
". , , A. .A, . i20 136 £'6 120 168 216 120 168 TIKE AT WHICH DEATH OF THE EMBRYOS OCCURRED (IN HOURS).
fie
FIG. 1. Embryo death patterns of 17 serial passages of strain 6 of infectious bronchitis virus.
embryo passages of this strain. The IB immune birds remained asymptomatic for a 12-day observation period. The aafl harvested from the 9th and the 13 th passages was tested for bacterial contamination and proved to be sterile. DISCUSSION Table 1 may give the impression that the pathogenicity for chicken embryos of strain 6 could be used as a criterion to differentiate it from other vaccinal strains, since statistical analysis of the total percentage of deaths in strain 6 in relationship to the remaining five strains proves to be significant at S and 1 percent levels. The experiment, however, was repeated four times with strain 6, two times with strain 1 and once with the other strains. Each time the experiment was repeated, the differences in the total percentage of deaths were no longer statistically significant.
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
fested by strain 6, with a peak of 94 percent mortality within eight days following inoculation. It was interesting to note that only 9.2 percent of the dead embryos were curled, while dwarfism was present in all dead embryos. The length of the embryos along their long axis varied from a minimum of 22 mm. to a maximum of SO mm., while 28.2 percent of the dwarfed embryos ranged in length from 28 mm. to 34 mm. Simultaneous examination of the controls showed no gross lesions, with the exception of one egg in which the chorio-allantoic membrane presented numerous petechiae. The controls' average length was S3 mm.
349
BRONCHITIS VIRUS STRAINS
SUMMARY
An attempt was made to differentiate a field strain of infectious bronchitis virus
from five vaccinal strains by using the pathogenicity of each for chicken embryonating eggs (c.e.e.). Inconstant pathogenicity for c.e.e. and lack of a death pattern for embryos prevented such a differentiation. REFERENCES Adler, H. E., R. Yamamoto and R. A. Bankowski, 1954. A preliminary report of efficiency of various mediums for isolation of pleuropneumonialike organisms from exudates of birds with chronic respiratory diseases. Am. J. Vet. Res. I S : 463-465. Beaudette, F . R., and C. B. Hudson, 1937. Cultivation of the virus of infectious bronchitis. J. Am. Vet. Med. Assn. 90: 51-58. Cunningham, C. H., 1948. A Laboratory Guide in Virology. Minneapolis, Burgess Pub. Co. Fabricant, J., 1949. Studies on the diagnosis of Newcastle disease and infectious bronchitis of fowls. I I . The diagnosis of infectious bronchitis by virus isolation in chick embryos. Cornell Vet. 39: 414-431. Loomis, L. N., C. H. Cunningham, M. L. Gray and F. Thorp, Jr., 1950. Pathology of the chicken embryo infected with infectious bronchitis virus. Am. J. Vet. Res. 11: 245-251. Raggi, L. G., and R. A. Bankowski, 1956. Study of some commercially available infectious bronchitis vaccines. I. Response of chickens to seven infectious bronchitis vaccines. Am. J. Vet. Res. 17: 523-530.
NEWS AND NOTES (Continued from page 326) early diagnosis of fowl plague in the United States name on any poultry program was a guarantee of and its eradication under his supervision. He was good attendance. This was not limited to farmer audiences. His schools for instructing veterinarians author or co-author of 154 scientific papers and on poultry diseases were very popular in the early bulletins. 1930's. His encyclopedic knowledge of his subject He was a member of the Poultry Science Associaand his frankness in discussing poultry disease tion, and was Associate Editor of Poultry Science problems won him an enviable reputation. At times, from 1947 to 1951, the American Veterinary Medhis frankness may have irritated some in his audiical Association, the U. S. Livestock Sanitary Assoences but they went away knowing exactly where ciation, and Research Workers in Animal Diseases. he stood on any question. JAMES GARFIELD HALPIN was born in Odessa, Some of his outstanding contributions were: the New York in 1883, and was the first student to major in poultry husbandry at Cornell. He was a discovery of the cause of laryngotracheitis and the subsequent development of a vaccine to prevent it, pioneer then and has been one ever since. His first the discovery of strains of Newcastle disease virus job after graduation was as Instructor at Rhode Island State College, working from 1905 to 1906 and the prevention of the disease by vaccination, the discovery of swine erysipelas in turkeys, and his with Dr. Cooper Curtice who was carrying on (Continued on page 353)
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
It was concluded that the pathogenicity for chicken embryos was an unstable trait of the IBV strains studied and, therefore, was not usable as a means of identification. Differences among these vaccine strains, however, were demonstrated when they were inoculated into chickens and their response studied (Raggi and Bankowski, 1956). It was believed necessary to determine whether or not the death pattern per se was a constant characteristic of strain 6, irrespective of the number of times the strain was passed serially through chicken embryonating eggs. Although care was taken in passing the aafl shortly after death of the embryos of each passage, it was not possible to stabilize time and pattern of death of chicken embryonating eggs after 17 serial passages. Apparently numerous passages are required of a strain of IBV before stabilizing its death pattern for chicken embryos. This procedure becomes impractical for identification of a strain of IBV.
ISAACKS, REID, DAVIES, QUISENBEERY AND COUCH
Singsen, E. P., 1955. Feeding and management systems for growing pullets and their effect on adult performance. Abstracts of papers, Texas Nutrition Conf. p. 57. Stephenson, A. B., and R. L. Bryant, 1944. The value of sod range for starting chicks, growing pullets and laying hens. Virginia Agri. Expt. Sta. Bull. No. 362. Sunde, M. L., W. M. Cravens, H. R. Bird and J. G. Halpin, 1954. The effect of complete and incomplete growing diets ond subsequent performance of the laying hen. Poultry Sci. 33: 779-784. Winter, A. R., and K. F. Schlamb, 1948. Influence of range versus confinement rearing on growth feed consumption, egg production and livability. Poultry Sci. 27: 571-578.
A Study of the Behavior of Six Infectious Bronchitis Virus Strains in Chicken Embryos L. G. RAGGI AND R. G. RAYMOND*
School of Veterinary Medicine, University of California, Davis (Received for publication July 6, 1959)
HE RESPONSE of susceptible chickens to inoculation with some commercially available infectious bronchitis (IB) vaccines formed the subject of investigation of the first paper of this series (Raggi and Bankowski, 1956). The main objective of the present study was to investigate whether or not the pathogenicity of the above IB vaccine strains for chicken embryos was sufficiently characteristic for use as a criterion to differentiate a field strain from a vaccinal strain of IB. An attempt was also made to stabilize the time and the pattern of death of normal chicken embryos inoculated with one of the strains (No. 6) of infectious bronchitis virus (IBV).
T
* Present address: Heisdorf & Nelson Farms, Inc., Redmond, Washington.
MATERIALS AND PROCEDURE
IB vaccinal strains obtained directly from the manufacturers were stored at 2°C. for a few days before being tested. The vaccines were reconstituted by aspirating the diluent with a sterile syringe and needle inserted through the rubber stopper previously swabbed with 95 percent ethyl alcohol, and gently flamed. The diluent was introduced aseptically into the bottle containing the lyophilized vaccine. Each inoculum was tested for bacterial, PPLO (Adler et al., 1954) and Newcastle disease virus contamination, with negative results. Strain 6 was originally isolated from a field outbreak of IB by Dr. H. Van Roekel of the University of Massachusetts. The infected amnio-allantoic fluid (aafl) of the chicken embryo passage constituted the inoculum. This aafl was also chosen to study
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
Payne, L. F., and C. L. Gish, 1943. Grass and alfalfa as silage forage and meal for poultry. Kansas Agri. Expt. Sta. Bull. No. 320. Pepper, W. F., S. J. Slinger, H. L. Orr and E. S. Snyder, 1959. Effect of high and low energy diets and range versus confinement rearing on egg production and quality of fresh and held eggs. Poultry Sci. 38: 379-38S. Schneider, A. J., B. B. Bohren and V. L. Anderson, 1955. The effect of restricted feeding on several genetically controlled characters in the fowl. Poultry Sci. 34: 691-702. Singsen, E. P., L. D. Matterson, A. Kozeff and L. D. Stinson, 1954. The effects of feeding high and low efficiency rations to growing pullets on their subsequent laying performance. Poultry Sci. 33: 1081.
347
BRONCHITIS VIRUS STRAINS
(1) dwarfism and "curling"; (2) size; (3) presence of hemorrhages or other gross lesions; (4) length along the long axis. Dwarfism and curling were previously described (Beaudette and Hudson, 1937; Loomis et al., 1950; Fabricant, 1949) as changes observed in embryos infected with
IBV. Cutaneous hemorrhages are observed in embryos infected with Newcastle disease virus. Each strain was inoculated into 60 c.e.e. Twelve additional c.e.e. of the same source and age were used as normal controls. RESULTS
Table 1 indicates that, with the exception of strain 6, no mortality was experienced with any of the IBV strains in the first 48 hours after inoculation. Hemorrhages were not noticed in the dead embryos. The embryos inoculated with strain 1 appeared dwarfed and curled. The pathogenicity of this strain was further evidenced by a 70.5 percent mortality within ten days of observation. Strains 2 and 3 had similar effects. All the dead embryos examined from eggs inoculated with both strains appeared fully developed and no curling was noticeable. Strain 4 behaved similarly to strains 2 and 3, with the exception that a few of the dead embryos were undeveloped and curled. Strain 5 caused a total mortality of 52.0 percent. The majority of deaths (40 percent) occurred on the third and fourth day after inoculation. The greatest egg-killing power was mani-
TABLE 1.—Death pattern of six infectious bronchitis virus strains in embryos Percentage of eggs dead on a daily basis IBV strains 1* 2** 3** 4*** 5**** 6*
1
2
3
4
5
6
7
8
9
10
0 0 0 0 0 0
0 0 0 0 0 6
13 18.2 8.8 4.4 26 10
13.3 15.9 4.4 11.1 14 14
8.8 13.6 4.4 11.1 2 16
11.1 2.3 6.6 8.8 0 28
2.2 2.3 2.2 2.2 10 10
4.4 4.6 0 0 0 10
6.6 0 0 0 0
11.1 2.3 17.7 20.0 0
Total percentage of deaths 70.5 59.2 44.1 57.6 52.0 94.0
* Most of the dead embryos were found to be incompletely developed, and "curled"; maximal length was 50 mm. ** All of the dead embryos examined appeared to be fully developed and no curling was noticeable. When strains 2 and 3 were inoculated into chickens susceptible to IB, their immunogenicity was not satisfactory. *** Only a few of the dead embryos were undeveloped and curled. **** Dwarfism present in the majority of dead embryos.
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
the death pattern of chicken embryonating eggs (c.e.e.) through 17 serial passages. To eliminate as many variables as possible, the c.e.e. were obtained from one source. After incubation for nine days, the eggs were candled, and an area of the shell above the air cell swabbed with 95 percent alcohol, painted with 8 percent tincture of iodine, drilled, and painted again with iodine. To avoid cross-contamination of strains, one strain was tested at a time. Each egg was inoculated according to the method of Cunningham (1948) with 0.2 ml. of the reconstituted vaccine or undiluted aafi. The holes were sealed with Duco cement and the eggs incubated at 35.5°C. Previous trials indicated that this temperature was most favorable for growth of IB virus. The eggs were candled three times a day. Embryos that died on or before the tenth day of incubation were opened and examined for:
348
L. G. RAGGI AND R. G. RAYMOND
Of the six strains studied, strain 1 appeared to predominate in producing curling, which was observed in 30.S percent of the embryos, with two cases of schistosomas; 70.5 percent of the embryos were dead within ten days following inoculation. Death pattern oj c.e.e. inoculated with strain 6. Strain 6 was chosen to study the death pattern in embryos. Fig. 1 indicates that 17 serial passages of the aafl of freshly dead embryos did not result in a constant and reproducible death pattern. Eggs of the sixth passage, inoculated with aafl of an embryo that died on the 48th hour following inoculation, all died at approximately the 48th hour, but the successive passages clearly showed an irregularity of the death curve. Possible changes in pathogenicity, or possible adaptation of the virus to embryonic tissue with a loss of pathogenicity for growing birds, were tested by inoculation of susceptible birds with aafl of the 9th and 13 th serial passages, respectively. Two IB immune birds were also inoculated intratracheally and intramuscularly to detect, if present, contamination with other pathogenic viruses of chickens. Characteristic and typical IB signs of comparable severity were observed within 24-48 hours in birds inoculated with both the 9th and the 13th
PASSAGE 1
: -
A
LL..
PASSAGE 7
:
PASSAGE 6
PASSAGE 2
;.d PASSAGE 4
,A... PASSAGE 14
.
PASSAGE 9
PASSAGE 15 .
PASSAGE 10
PASSAGE 16 „
\,Ax,.:
A/\... PASSAGE II
PASSAGE 5
: PASSAGE 6
PASSAGE 13 -
PASSAGE 17 _
..A^.."7\A...'
:
PASSAGE 12
". , , A. .A, . i20 136 £'6 120 168 216 120 168 TIKE AT WHICH DEATH OF THE EMBRYOS OCCURRED (IN HOURS).
fie
FIG. 1. Embryo death patterns of 17 serial passages of strain 6 of infectious bronchitis virus.
embryo passages of this strain. The IB immune birds remained asymptomatic for a 12-day observation period. The aafl harvested from the 9th and the 13 th passages was tested for bacterial contamination and proved to be sterile. DISCUSSION Table 1 may give the impression that the pathogenicity for chicken embryos of strain 6 could be used as a criterion to differentiate it from other vaccinal strains, since statistical analysis of the total percentage of deaths in strain 6 in relationship to the remaining five strains proves to be significant at S and 1 percent levels. The experiment, however, was repeated four times with strain 6, two times with strain 1 and once with the other strains. Each time the experiment was repeated, the differences in the total percentage of deaths were no longer statistically significant.
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
fested by strain 6, with a peak of 94 percent mortality within eight days following inoculation. It was interesting to note that only 9.2 percent of the dead embryos were curled, while dwarfism was present in all dead embryos. The length of the embryos along their long axis varied from a minimum of 22 mm. to a maximum of SO mm., while 28.2 percent of the dwarfed embryos ranged in length from 28 mm. to 34 mm. Simultaneous examination of the controls showed no gross lesions, with the exception of one egg in which the chorio-allantoic membrane presented numerous petechiae. The controls' average length was S3 mm.
349
BRONCHITIS VIRUS STRAINS
SUMMARY
An attempt was made to differentiate a field strain of infectious bronchitis virus
from five vaccinal strains by using the pathogenicity of each for chicken embryonating eggs (c.e.e.). Inconstant pathogenicity for c.e.e. and lack of a death pattern for embryos prevented such a differentiation. REFERENCES Adler, H. E., R. Yamamoto and R. A. Bankowski, 1954. A preliminary report of efficiency of various mediums for isolation of pleuropneumonialike organisms from exudates of birds with chronic respiratory diseases. Am. J. Vet. Res. I S : 463-465. Beaudette, F . R., and C. B. Hudson, 1937. Cultivation of the virus of infectious bronchitis. J. Am. Vet. Med. Assn. 90: 51-58. Cunningham, C. H., 1948. A Laboratory Guide in Virology. Minneapolis, Burgess Pub. Co. Fabricant, J., 1949. Studies on the diagnosis of Newcastle disease and infectious bronchitis of fowls. I I . The diagnosis of infectious bronchitis by virus isolation in chick embryos. Cornell Vet. 39: 414-431. Loomis, L. N., C. H. Cunningham, M. L. Gray and F. Thorp, Jr., 1950. Pathology of the chicken embryo infected with infectious bronchitis virus. Am. J. Vet. Res. 11: 245-251. Raggi, L. G., and R. A. Bankowski, 1956. Study of some commercially available infectious bronchitis vaccines. I. Response of chickens to seven infectious bronchitis vaccines. Am. J. Vet. Res. 17: 523-530.
NEWS AND NOTES (Continued from page 326) early diagnosis of fowl plague in the United States name on any poultry program was a guarantee of and its eradication under his supervision. He was good attendance. This was not limited to farmer audiences. His schools for instructing veterinarians author or co-author of 154 scientific papers and on poultry diseases were very popular in the early bulletins. 1930's. His encyclopedic knowledge of his subject He was a member of the Poultry Science Associaand his frankness in discussing poultry disease tion, and was Associate Editor of Poultry Science problems won him an enviable reputation. At times, from 1947 to 1951, the American Veterinary Medhis frankness may have irritated some in his audiical Association, the U. S. Livestock Sanitary Assoences but they went away knowing exactly where ciation, and Research Workers in Animal Diseases. he stood on any question. JAMES GARFIELD HALPIN was born in Odessa, Some of his outstanding contributions were: the New York in 1883, and was the first student to major in poultry husbandry at Cornell. He was a discovery of the cause of laryngotracheitis and the subsequent development of a vaccine to prevent it, pioneer then and has been one ever since. His first the discovery of strains of Newcastle disease virus job after graduation was as Instructor at Rhode Island State College, working from 1905 to 1906 and the prevention of the disease by vaccination, the discovery of swine erysipelas in turkeys, and his with Dr. Cooper Curtice who was carrying on (Continued on page 353)
Downloaded from http://ps.oxfordjournals.org/ at Karolinska Institutet University Library on May 25, 2015
It was concluded that the pathogenicity for chicken embryos was an unstable trait of the IBV strains studied and, therefore, was not usable as a means of identification. Differences among these vaccine strains, however, were demonstrated when they were inoculated into chickens and their response studied (Raggi and Bankowski, 1956). It was believed necessary to determine whether or not the death pattern per se was a constant characteristic of strain 6, irrespective of the number of times the strain was passed serially through chicken embryonating eggs. Although care was taken in passing the aafl shortly after death of the embryos of each passage, it was not possible to stabilize time and pattern of death of chicken embryonating eggs after 17 serial passages. Apparently numerous passages are required of a strain of IBV before stabilizing its death pattern for chicken embryos. This procedure becomes impractical for identification of a strain of IBV.