الفهرس 
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Abstract
Abstract
Foot-and-mouth disease (FMD) is a highly contagious disease affecting cloven-hoofed animals including cattle and buffaloes, with a severe economic impact. Foot-and-mouth disease virus (FMDV) serotypes A, O, and South African Territories (SAT2) are endemic in Egypt, which are represented in different topotypes and lineages. Continuous mutations and the emergence of new topotypes require frequent monitoring and characterization of FMDV circulating strains. In this current study, 233 field samples were collected from eight Egyptian governorates between 2014 and January 2022. The isolated samples were subjected to molecular characterization, revealed that they are O-EA3 and A-Iran 05. Antigen was prepared form identified isolates and used for the preparation of an inactivated heptavalent FMD vaccine (APHTHOVAC 7) adjuvanted with Montanide ISA 206 oil. The vaccine effectiveness was carried out in 200 adult dairy cattle under field conditions. The animals were vaccinated with the prepared vaccine, boostered after 30 days and tested for seroconversion using a virus neutralization test at 30-, 60-, and 120-days post-vaccination. The vaccine efficacy was evaluated in three groups of 6- to 8-month-old calves (six calves each group) as they were vaccinated with formulated vaccine and challenged after 28 days by intradermolingual inoculation with 104 50% cattle infective dose of wild FMDV serotypes A, O, or SAT-2. Two non-vaccinated calves served as controls during the challenge test. The molecular characterization revealed that samples belonged to A-Iran 05 and O-EA3 strains. Serum samples collected after at 30-, 60-, and 120-days post-vaccination contained high titers of protective antibodies (≥ 1/32; i.e., 1.5 log10), and persisted until the end of the study period with a peak value at around 60 days post-vaccination. Moreover, the challenged calves exhibited complete protection against the wild strains compared to the control group. In conclusion, the developed heptavalent FMD vaccine proved to be potent and capable of providing a protective immune response under field conditions.
Key words: Foot and mouth disease, ISA 206 oil, heptavalent vaccine.