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Preliminary field test of lyophilised contagious caprine pleuropneumonia vaccine
SHORT
COMMUNICATIONS
Research in Veterinary Science 1991, 50, 240-241
Preliminary field test of lyophilised contagious caprine pleuropneumonia vaccine F. R. RURANGIRWA, T. C. McGUIRE, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, USA, L. MBAI, L. NDUNG'U, A. WAMBUGU, Kenya Agricultural
Research Institute, National Veterinary Research Centre, Kabete, Kenya
Fifty goats were immunised in the field against contagious caprine pleuropneumonia (cope) using a single dose (0.15 rag) of lyophilised, saponin killed Mycoplasma strain F38. Two months after vaccination, these goats together with 50 unimmunised control goats were challenged by contact with goats experimentally infected with CCPP. Twelve vaccinates and 14 controls died of diarrhoea due to salmonella infection during the first two weeks after challenge. The remaining immunised goats (38) with the exception of two goats which had elevated temperatures were protected from ccPP. Of the remaining 36 control goats, 30 contracted ccPP at a mean of 39 ( a= 14.3 SD) days after challenge and 27 of them died. These results show that the lyophilised killed F38 vaccine conferred 100 per cent protection against mortality and 95 per' cent protection against clinical disease caused by Mycoplasma species strain F38. CONTAGIOUS caprine pleuropneumonia (CCPP)caused by Mycoplasma strain F38 (MacOwan and Minette 1976) is the most serious infectious disease of goats in Kenya, causing high mortality and great economic loss. The disease occurs in epidemics in all areas of the country. Current efforts are directed towards controlling the disease by vaccination. An inactivated ccPP vaccine which is effective and practical has been developed (Rurangirwa et al 1987a). These conclusions are based on data which demonstrate that a single dose can induce an immune response completely protecting goats against challenge for at least one year (Rurangirwa et al 1987a). Also, the vaccine can be stored in lyophilised form at room temperature for at least one year (Rurangirwa et al 1987a). These experiments were done under controlled conditions in which the immunised and control goats were challenged by being enclosed in a room with experimentally infected goats throughout the experimental period. This contact challenge was very severe, but could only be performed on a limited number of goats. To show the tisefulness of the vaccine under more natural conditions, the present authors carried out a limited but controlled field trial using more goats. One hundred and fifteen, one-year-old, goats from a single farm in Machakos District of Kenya, were screened for antibodies to F38 using a latex agglutination test (Rurangirwa et al 1987b) and an enzyme-linked immunosorbent assay (Bari 1984), and 100 of them which lacked
antibody to ccPP were purchased. Fifty of the goats in the field were immunised subcutaneously with a single dose (0- 15 mg) of the lyophilised, saponin killed ccPP vaccine (Rurangirwa et al 1987a) while the remaining 50 were left as unimmunised controls. All the goats were maintained on the same farm for two months and then transported to Kabete Veterinary Laboratory for contact challenge. The challenge was carried out by housing the 100 goats with five goats infected with F38 by endobronchial intubation (MacOwan and Minette 1976). During contact challenge, the two groups were grazed during the day and housed at night together with the five experimentally infected goats. All goats were examined daily and their rectal temperatures recorded. An autopsy was performed on any goat that died; the gross lesions recorded and specimens of lung, mediastinal lymph nodes and pleural fluid taken for isolation of mycoplasma and bacteria. The trial was carried out for four months after challenge and the surviving goats were euthanased and autopsies carried out as described above. Mycoplasma were isolated using Newing's tryptose broth (Gourlay 1964) and their identity as F38 was confirmed by growth inhibition (Rnrangirwa et al 1987c). Twelve vaccinates and 14 controls died of diarrhoea due to salmonella infection within the first two weeks after the movement of the goats to the Kabete Veterinary Laboratory. None of these goats had lung lesions and no F38 organisms were isolated from lung or lymph node tissues. Table I shows the outcome of the contact challenge for the remaining vaccinates (38 goats) and controls (36 goats). Thirty control goats developed pyrexia at a mean of 39 (-4- 14-3 SD) days after exposure. Twenty-seven of the 30 affected control goats died of ccPP at a mean 8.1 ( ± 2.33 SD) days after pyrexia began and three recovered. Four months after contact challenge, the three recovered control goats had adhesions of the cardiac and apical lobes to the thoracic wall but F38 organisms were not isolated from their tissues. The
TABLE 1 : Immunity of goats to challenge with F38 two months after a single field vaccination with lyophilised F38 vaccine
Group
Reprint requests to F. R. Rurangirwa, SR-CRSP,Box 58137, Nairobi, Kenya
Controls Vaccinated
240
Number infected/ number challenged
Number dead/ number challenged
Incubation period (mean days ± SD)
30/36 2/38
27/36 0/38
3 9 - 0 ± 14-3 41 • 0, 6 2 . 0
P r e l i m i n a r y f i e l d test o f CCPP vaccine
remaining six control goats had no signs of disease and when they were euthanased and examined at the end of four m o n t h s , there were no lesions and F38 organisms were not isolated from their tissues. Failure of six of 36 control goats to contract ccPP is in contrast to containment experiments in which almost 100 per cent infection occurred in the contact challenges (Rurangirwa et al 1987a). A morbidity and mortality rate of 60 to 80 per cent has been reported for the field outbreaks of ccPP (MacOwan and Minette 1977). The experimental conditions for the present study were set to mimic field conditions as opposed to containment throughout the experimental period. Therefore, the failure of six controls to show any signs of disease m a y be attributed to a less severe challenge than was previously used (Rurangirwa et al 1987a). The recovery of the three control goats from ccPP after showing clinical signs indicates that a small number of goats m a y recover from ccPP, especially if they are not subjected to movement stress in search of food and water. All the surviving vaccinates withstood the challenge. There was a temperature elevation in two of the goats (41 and 62 days after challenge) which returned to normal after two days. There was no pyrexia and no signs of disease in the remaining 36 vaccinated goats during the four m o n t h experimental period (Table 1). At the end of the experiment active lesions were not seen in the 36 euthanased vaccinated goats without clinical signs and F38 was not isolated from their tissues. However in the two vaccinates which had a temperature reaction adhesions were present in the thoracic cavity, but F38 was not isolated from their tissues. This finding m a y be related to individual variation or to other u n k n o w n causes. Similar observations have been reported before (Rurangirwa et al 1987a). In conclusion, one dose of lyophilised F38 vaccine induced an immunity in goats that protected totally against mortality and was 95 per cent efficacious against clinical disease. In the two vaccinated goats that had pyrexia, no detectable carrier state resulted. Therefore, this vaccine is suitable for use in control programmes for ccPP.
241
Acknowledgements We thank Joseph Buyu and A b u Oriko for technical assistance. This research was carried out as a part of the United States Agency for International Development Title XII Small Ruminant Collaborative Research Support Program under grant A I D / D S A N / X I I - G - 0 0 4 9 , in collaboration with the Kenya Agricultural Research Institute, Kenya. This paper is published with the permission of the director of the Kenya Agricultural Research Institute.
References BARI, J. K. (1984) Development of an enzyme-linked immunosorbent assay for detection of contagious caprine pleuropneumonia in gnats. MSc thesis, Washington State University GOURLAY, R. N. (1964) Antigenicity ofMycoplasma mycoides. 1. Examination of body fluids from cases of contagious bovine pleuropneumonia. Research in Veterinary Science 5, 473-482 MacOWAN, K. J. & MINETTE, J. E. (1976) A mycoplasma from acute contagious eaprine pleuropneumonia. Tropical Animal Health and Production 8, 91-95 MacOWAN, K. J. & MINETTE, J. E. (1977) The role of Mycoplasma strain F38 in contagious caprine pleuropneumonia in Kenya. Veterinary Record 101,380-381 RURANGIRWA, F. R., McGUIRE, T. C., KIBOR, A. & CHEMA, A. (1987a) An inactivated vaccine for contagious caprine pleuropneumonia. Veterinary Record 121,397-402 RURANGIRWA, F. R., McGUIRE, T. C., KIBOR, A. & CHEMA, S. (1987b) A latex agglutination test for field diagnosis of contagious caprine pleuropneumonia. Veterinary Record 121, 191-193 RURANGIRWA, F. R., McGUIRE, T. C., MUSOKE, A. J. & KIBOR, A. (1987c) Differentiation of F38 myeoplasmas causing contagious caprine pleuropneumonia with a growth inhibiting monoelonal antibody. Infection and Immunity 55, 3219-3220
Received April 24, 1990 Accepted September 7, 1990
COMMUNICATIONS
Research in Veterinary Science 1991, 50, 240-241
Preliminary field test of lyophilised contagious caprine pleuropneumonia vaccine F. R. RURANGIRWA, T. C. McGUIRE, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, USA, L. MBAI, L. NDUNG'U, A. WAMBUGU, Kenya Agricultural
Research Institute, National Veterinary Research Centre, Kabete, Kenya
Fifty goats were immunised in the field against contagious caprine pleuropneumonia (cope) using a single dose (0.15 rag) of lyophilised, saponin killed Mycoplasma strain F38. Two months after vaccination, these goats together with 50 unimmunised control goats were challenged by contact with goats experimentally infected with CCPP. Twelve vaccinates and 14 controls died of diarrhoea due to salmonella infection during the first two weeks after challenge. The remaining immunised goats (38) with the exception of two goats which had elevated temperatures were protected from ccPP. Of the remaining 36 control goats, 30 contracted ccPP at a mean of 39 ( a= 14.3 SD) days after challenge and 27 of them died. These results show that the lyophilised killed F38 vaccine conferred 100 per cent protection against mortality and 95 per' cent protection against clinical disease caused by Mycoplasma species strain F38. CONTAGIOUS caprine pleuropneumonia (CCPP)caused by Mycoplasma strain F38 (MacOwan and Minette 1976) is the most serious infectious disease of goats in Kenya, causing high mortality and great economic loss. The disease occurs in epidemics in all areas of the country. Current efforts are directed towards controlling the disease by vaccination. An inactivated ccPP vaccine which is effective and practical has been developed (Rurangirwa et al 1987a). These conclusions are based on data which demonstrate that a single dose can induce an immune response completely protecting goats against challenge for at least one year (Rurangirwa et al 1987a). Also, the vaccine can be stored in lyophilised form at room temperature for at least one year (Rurangirwa et al 1987a). These experiments were done under controlled conditions in which the immunised and control goats were challenged by being enclosed in a room with experimentally infected goats throughout the experimental period. This contact challenge was very severe, but could only be performed on a limited number of goats. To show the tisefulness of the vaccine under more natural conditions, the present authors carried out a limited but controlled field trial using more goats. One hundred and fifteen, one-year-old, goats from a single farm in Machakos District of Kenya, were screened for antibodies to F38 using a latex agglutination test (Rurangirwa et al 1987b) and an enzyme-linked immunosorbent assay (Bari 1984), and 100 of them which lacked
antibody to ccPP were purchased. Fifty of the goats in the field were immunised subcutaneously with a single dose (0- 15 mg) of the lyophilised, saponin killed ccPP vaccine (Rurangirwa et al 1987a) while the remaining 50 were left as unimmunised controls. All the goats were maintained on the same farm for two months and then transported to Kabete Veterinary Laboratory for contact challenge. The challenge was carried out by housing the 100 goats with five goats infected with F38 by endobronchial intubation (MacOwan and Minette 1976). During contact challenge, the two groups were grazed during the day and housed at night together with the five experimentally infected goats. All goats were examined daily and their rectal temperatures recorded. An autopsy was performed on any goat that died; the gross lesions recorded and specimens of lung, mediastinal lymph nodes and pleural fluid taken for isolation of mycoplasma and bacteria. The trial was carried out for four months after challenge and the surviving goats were euthanased and autopsies carried out as described above. Mycoplasma were isolated using Newing's tryptose broth (Gourlay 1964) and their identity as F38 was confirmed by growth inhibition (Rnrangirwa et al 1987c). Twelve vaccinates and 14 controls died of diarrhoea due to salmonella infection within the first two weeks after the movement of the goats to the Kabete Veterinary Laboratory. None of these goats had lung lesions and no F38 organisms were isolated from lung or lymph node tissues. Table I shows the outcome of the contact challenge for the remaining vaccinates (38 goats) and controls (36 goats). Thirty control goats developed pyrexia at a mean of 39 (-4- 14-3 SD) days after exposure. Twenty-seven of the 30 affected control goats died of ccPP at a mean 8.1 ( ± 2.33 SD) days after pyrexia began and three recovered. Four months after contact challenge, the three recovered control goats had adhesions of the cardiac and apical lobes to the thoracic wall but F38 organisms were not isolated from their tissues. The
TABLE 1 : Immunity of goats to challenge with F38 two months after a single field vaccination with lyophilised F38 vaccine
Group
Reprint requests to F. R. Rurangirwa, SR-CRSP,Box 58137, Nairobi, Kenya
Controls Vaccinated
240
Number infected/ number challenged
Number dead/ number challenged
Incubation period (mean days ± SD)
30/36 2/38
27/36 0/38
3 9 - 0 ± 14-3 41 • 0, 6 2 . 0
P r e l i m i n a r y f i e l d test o f CCPP vaccine
remaining six control goats had no signs of disease and when they were euthanased and examined at the end of four m o n t h s , there were no lesions and F38 organisms were not isolated from their tissues. Failure of six of 36 control goats to contract ccPP is in contrast to containment experiments in which almost 100 per cent infection occurred in the contact challenges (Rurangirwa et al 1987a). A morbidity and mortality rate of 60 to 80 per cent has been reported for the field outbreaks of ccPP (MacOwan and Minette 1977). The experimental conditions for the present study were set to mimic field conditions as opposed to containment throughout the experimental period. Therefore, the failure of six controls to show any signs of disease m a y be attributed to a less severe challenge than was previously used (Rurangirwa et al 1987a). The recovery of the three control goats from ccPP after showing clinical signs indicates that a small number of goats m a y recover from ccPP, especially if they are not subjected to movement stress in search of food and water. All the surviving vaccinates withstood the challenge. There was a temperature elevation in two of the goats (41 and 62 days after challenge) which returned to normal after two days. There was no pyrexia and no signs of disease in the remaining 36 vaccinated goats during the four m o n t h experimental period (Table 1). At the end of the experiment active lesions were not seen in the 36 euthanased vaccinated goats without clinical signs and F38 was not isolated from their tissues. However in the two vaccinates which had a temperature reaction adhesions were present in the thoracic cavity, but F38 was not isolated from their tissues. This finding m a y be related to individual variation or to other u n k n o w n causes. Similar observations have been reported before (Rurangirwa et al 1987a). In conclusion, one dose of lyophilised F38 vaccine induced an immunity in goats that protected totally against mortality and was 95 per cent efficacious against clinical disease. In the two vaccinated goats that had pyrexia, no detectable carrier state resulted. Therefore, this vaccine is suitable for use in control programmes for ccPP.
241
Acknowledgements We thank Joseph Buyu and A b u Oriko for technical assistance. This research was carried out as a part of the United States Agency for International Development Title XII Small Ruminant Collaborative Research Support Program under grant A I D / D S A N / X I I - G - 0 0 4 9 , in collaboration with the Kenya Agricultural Research Institute, Kenya. This paper is published with the permission of the director of the Kenya Agricultural Research Institute.
References BARI, J. K. (1984) Development of an enzyme-linked immunosorbent assay for detection of contagious caprine pleuropneumonia in gnats. MSc thesis, Washington State University GOURLAY, R. N. (1964) Antigenicity ofMycoplasma mycoides. 1. Examination of body fluids from cases of contagious bovine pleuropneumonia. Research in Veterinary Science 5, 473-482 MacOWAN, K. J. & MINETTE, J. E. (1976) A mycoplasma from acute contagious eaprine pleuropneumonia. Tropical Animal Health and Production 8, 91-95 MacOWAN, K. J. & MINETTE, J. E. (1977) The role of Mycoplasma strain F38 in contagious caprine pleuropneumonia in Kenya. Veterinary Record 101,380-381 RURANGIRWA, F. R., McGUIRE, T. C., KIBOR, A. & CHEMA, A. (1987a) An inactivated vaccine for contagious caprine pleuropneumonia. Veterinary Record 121,397-402 RURANGIRWA, F. R., McGUIRE, T. C., KIBOR, A. & CHEMA, S. (1987b) A latex agglutination test for field diagnosis of contagious caprine pleuropneumonia. Veterinary Record 121, 191-193 RURANGIRWA, F. R., McGUIRE, T. C., MUSOKE, A. J. & KIBOR, A. (1987c) Differentiation of F38 myeoplasmas causing contagious caprine pleuropneumonia with a growth inhibiting monoelonal antibody. Infection and Immunity 55, 3219-3220
Received April 24, 1990 Accepted September 7, 1990