Protective efficacy of an inactivated vaccine against rabbit hemorrhagic disease virus 2 prepared from a local isolate in Egypt
Ola Youssef M. Youssef;
Abstract
During the present work, the RHD was diagnosed from 11 infected farms from Qalubia governorate during 2019 using hemagglutination test, animal inoculation and RTPCR, The RHDV 2 was isolated and a homologous vaccine was prepared against RHDV2 using Montanid ISA 206 or aluminum hydroxide gel adjuvants.
The liver samples were collected from suspected cases in El-Qalubia governorate during 2019. 10 out of 11 tested viral samples were able to agglutinate human type (O) RBCs with HA titers ranging from 26 to 213. The molecular characterization of Egyptian isolates revealed that 10 out of 11 viral samples were positive by VP60 based-RT-PCR. R5&R6 isolates are clustered with Egyptian RHDV2 strain but in a separate branch & divergent from each other, with high bootstrapping value (1000). So, there are necessity to update vaccine strain and prepare vaccines against RHDV2 adjuvanted with aluminum hydroxide gel or montanide ISA 206. The two vaccines were prepared with diverse adjuvants according to the standard procedures keeping the antigen amount (210 HAU/1ml) constant within the two vaccine formulations.
The prepared vaccines were satisfactory for purity & safety as there are no any clinical signs and pathological lesions observed in vaccinated rabbits by double field doses of vaccines. The vaccine potency is determined by HI and challenge test. The mean HI titers in aluminum hydroxide gel vaccine was 6, 7.7, 8.9 & 9.1 log2, respectively in 1st, 2nd, 3rd, & 4th WPV while, in oil adjuvanted vaccine it reaches to 6.7,
8.7, 9.2 & 9.5 log2, respectively in 1st, 2nd, 3rd, & 4th WPV.
The challenge test results revealed protection percent 60%, 70%, 90%, 90% for aluminum hydroxide gel vaccine compared to 70%, 90%, 100%, 100% in case of montanide ISA 206 vaccine respectively in 1st, 2nd, 3rd & 4th WPV. After challenge at 4th WPV, the immune response in montanide oil vaccine is additionally more increased than aluminum hydroxide gel vaccine. So, it was recommended for continuous monitoring & molecular analysis of the RHDV strains present in Egypt should be performed to update the vaccine strain and avoid vaccination failure. The vaccine formulation should contain montanide ISA 206 as adjuvant instead of aluminum hydroxide gel to protect rapidly against highly evolved RHDV2
The liver samples were collected from suspected cases in El-Qalubia governorate during 2019. 10 out of 11 tested viral samples were able to agglutinate human type (O) RBCs with HA titers ranging from 26 to 213. The molecular characterization of Egyptian isolates revealed that 10 out of 11 viral samples were positive by VP60 based-RT-PCR. R5&R6 isolates are clustered with Egyptian RHDV2 strain but in a separate branch & divergent from each other, with high bootstrapping value (1000). So, there are necessity to update vaccine strain and prepare vaccines against RHDV2 adjuvanted with aluminum hydroxide gel or montanide ISA 206. The two vaccines were prepared with diverse adjuvants according to the standard procedures keeping the antigen amount (210 HAU/1ml) constant within the two vaccine formulations.
The prepared vaccines were satisfactory for purity & safety as there are no any clinical signs and pathological lesions observed in vaccinated rabbits by double field doses of vaccines. The vaccine potency is determined by HI and challenge test. The mean HI titers in aluminum hydroxide gel vaccine was 6, 7.7, 8.9 & 9.1 log2, respectively in 1st, 2nd, 3rd, & 4th WPV while, in oil adjuvanted vaccine it reaches to 6.7,
8.7, 9.2 & 9.5 log2, respectively in 1st, 2nd, 3rd, & 4th WPV.
The challenge test results revealed protection percent 60%, 70%, 90%, 90% for aluminum hydroxide gel vaccine compared to 70%, 90%, 100%, 100% in case of montanide ISA 206 vaccine respectively in 1st, 2nd, 3rd & 4th WPV. After challenge at 4th WPV, the immune response in montanide oil vaccine is additionally more increased than aluminum hydroxide gel vaccine. So, it was recommended for continuous monitoring & molecular analysis of the RHDV strains present in Egypt should be performed to update the vaccine strain and avoid vaccination failure. The vaccine formulation should contain montanide ISA 206 as adjuvant instead of aluminum hydroxide gel to protect rapidly against highly evolved RHDV2
Other data
| Title | Protective efficacy of an inactivated vaccine against rabbit hemorrhagic disease virus 2 prepared from a local isolate in Egypt | Other Titles | الفاعليه الوقائيه لللقاح المثبط لفيروس النزف الدموى فى الارانب-2 المحضر من معزوله محليه من مصر | Authors | Ola Youssef M. Youssef | Issue Date | 2020 |
Attached Files
| File | Size | Format | |
|---|---|---|---|
| BB1999.pdf | 1.25 MB | Adobe PDF | View/Open |
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