Comparative Efficacy Of Passive And Active Immunization During Newcastle Disease (Nd) Outbreak In Broilers
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Publisher: 2007 Dissertation note: Newcastle disease is an economically important disease of poultry resulting in huge economic losses every year to the poultry farmers in Pakistan. To compare passive immunization and active immunization during outbreak of Newcastle disease a total of 140 chicks at 16th day of age were divided into seven groups (A, B, C, D, E, F and G) containing 20 birds in each. The level of maternal antibody in chicks, was determined by haemagglutination inhibition titres which revealed that it was the highest at one day and decreased with increasing age. Newcastle disease virus gifted from Dr. Shafqat Fatima Rehmani, Director, Poultry Vaccine Center, Karachi, Sindh was pathotyped by using MDT and ICPI. The Embryo Lethal Dose5o was calculated to be 1083h/0. imi and was found highly pathogenic. Infection was induced in birds through administrating 100 ELD5O1O631/0.lml of Velogenic Newcastle disease virus. Birds of group A, this group seved as a negative control. In group B, this group acted as a positive control. Infection was given by using 0.1 ml of 100 ELD50 of Velogenic Newcastle disease virus intranasally at 26 days of age. In group C, at 16th days of age, all birds in this group were vaccinated with Newcastle disease virus vaccine. At 26th day of age, this group was exposed to infection as mentioned above. In group D, at 24th days of age, all birds in this group were vaccinated with Newcastle disease virus vaccine. At 26th day of age, infection was given by using 0.1 ml of 100 ELD50 of VNDV intranasally into individual bird.
In group E, infection and vaccination were given simultaneously at 31 day of age. In group F, In this group, infection was given by using 0.lml of 100 ELD50 of VNDV intranasally, at 26 days of age. When Newcastle disease symptoms were noticed, birds were vaccinated with lentogenic strain of Newcastle disease virus vaccine (Lasota, TAD- Germany) by using 0.5mllbird orally.
In group G, infection was given by using O.lml of 100 ELD50 of VND.V intranasally, at 26 days of age. When Newcastle disease symptoms were induced, birds were treated with 64 units of anti-NDV-haemagglutination inhibition yolk antibodies. Use of Lasota vaccine and preformed antibodies in yolk help in decreasing economical losses due to outbreak of Newcastle disease in poultry.
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Effect Of "In Process Quality Control "Factors On Efficacy Of Bird Flu Vaccine
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Publisher: 2008 Dissertation note: Bird Flu virus was recovered from lungs, trachea, spleen and fecal contents of the infected birds in 10 days old chicken embryos. HA activity and biological titer of the virus improved by serial passages in the 10 days old chicken embryos. This could be due to high rate of mutation of the Bird Flu virus with its successive passages. Formaldehyde and binary ethylenimine (BET) effectively inactivated the virus. However formaldehyde inactivated virus showed mitigation in HA activity during storage. The BET 5mM inactivate the virus with in 16 hours of incubation at ambient temperature (25°C) or 37°C. It has minimal detrimental effect on the HA activity of the virus, even during storage at refrigeration temperature.
Bird Flu virus vaccines without adjuvant induced poor antibody response in the vaccinated broilers. The vaccine containing aluminium hydroxide gel induced antibody response that reached at peak level on 1 8 days post priming and decline thereafter. The vaccine containing montanide (oil based vaccine) increased (90.5 GMT) up to 42 days of age. Boosting of the birds primed with gel based Bird Flu virus vaccine improved the production of antibody titer, while boosting of birds primed with oil based Bird Flu vaccine showed undetectable effect. This was due to increasing trend of antibody titer in oil based primed birds. Montanide based vaccines are therefore recommended for broiler, layers and breeders in high risk area of the disease.
Vaccines containing decreased infectivity titer induced decrease antibody titer in the vaccinated broilers. Bird Flu virus improved its HA activity and infectivity titer with serial passages in 10 days old chicken embryos. It is worth mentioning that serial passages of the virus tremendously decreased its antigenicity. It is therefore recommended to prepare commercial vaccine fom passage number 1-4, for effective immuno-prophylaxis.
The Bird Flu virus (H5N1) mutates very rapidly every time it passes through chicken embryos. It is therefore suggested to grow the virus at least in bio-safety level-ll plus (BSL-II +) laboratories.
On account of it high rate of mutation and risk of human health hazards it is suggested that Bird Flu virus (H5N1) may not be used in vaccine production, however other serotypes containing H5 and N antigen other than N1 may be used for production of commercial vaccine.
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