Abstract
The present study was undertaken to development of BHK-21 cell adapted inactivated vaccine of Newcastle disease virus (NDVgenotype VII) from the field isolate from broiler chicken in Egypt during 2015-2016. The isolatesof El-Giza/2015were classified by sequencing as velogenic NDV genotype VII d contains F protein cleavage site motifs (112RRQKRF117). Such virus was propagated in the BHK-21 cell line. and cell adapted virus was confirmed as NDV by reverse transcription-polymerase chain reaction (RT-PCR) using fusion gene-specific primers and used to develop inactivated vaccine adjuvanted with Montanide IMS 1313.Potency test revealed that Vaccinated chicks with 0.5ml of prepared NDV vaccine exhibited HI antibody titer of 8.6 log2 three weeks post vaccination with the highest titer (10.6 log2/ml) at the 6th-week post vaccination, and 3rd weeks post challenge test. Protective antibodies values were persisting till 12th weeks post vaccination. All chicken groups vaccinated with both prepared inactivated tissue culture vaccine using ISA 1313 and VSVRI inactivated ISA70 adjuvant vaccines were passed challenge test (97.5%,97%,96% protective efficiency to SPF chickens) against the isolated virulent NDV, while the control group could not provide any protective efficiency. The present study indicated that, BHK-21 cell adapted recent isolated NDV inactivated vaccine produced a satisfactory antibodies titre that efficient in control of the disease in Egypt.
Highlights
In the last period, the widespread use of different types of vaccines against newcastle disease virus failed to solve such major threats in the poultry industry (Fentie et al, 2014)
Routine vaccination strategy has reduced the disease, but repeated outbreaks of velogenic Newcastle disease virus (NDV) in domestic poultry highlight the importance of maintaining research on vaccine efficacy against newly isolated strains; there is a need to develop a vaccine(s) and/or vaccination strategies that provide a broader and effective immunity and prevent transmission of these viruses (Miller et al, 2010)
1.3.Adaptation of virus in BHK-21 cell line The confluent monolayer of BHK-21 cell line was infected with 1 ml of NDV inoculum for about 45-60 minutes, maintenance medium (MEM supplemented with 2% fetal bovine calf serum) was added and followed by incubation at 370C
Summary
The widespread use of different types of vaccines against newcastle disease virus failed to solve such major threats in the poultry industry (Fentie et al, 2014). Three Newcastle disease virus (NDV) strains isolated from outbreak in chickens in the Al-Sharkia province of Egypt in 2006 were determined (Mahmoud et al, 2011). Sequence of the F genes of 2006 Egyptian isolates are closely related to that of the 2005 suggesting that these strains are probably circulating in the vaccinated bird population in Egypt until development of an outbreak ( Mohamed et al, 2011). Newcastle disease virus (NDV) can readily infect different types of primary cells of avian and mammalian origin. The present study was designed for adaptation of the field isolate of NDV strain on BHK cell line, molecular confirmation together with preparation and evaluation of inactivated cell culture vaccine. For first Strand cDNA synthesis was conducted at 45°C for 45 minutes for reverse transcription (1 cycle), 94°C for 2 minutes for AMV RT inactivation and RNA/cDNA/primer denaturation (1cycle)
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