الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Foot and mouth disease was first animal disease to be attributed to a virus and the second virus to be discovered. FMDV belongs to the picornaviridec, a family of small RNA containing virus. The family consists of four genera including the Aphthoviruses which are classified into seven immunologically distinct serotypes: A, O, C, Asia 1, SAT1, SAT2 and SAT3, more than 65 subtypes and many antigenic variants. FMDV causes an economically devastating disease, affecting up to 70 species of eventoed ungulates, both domesticated and wild. The most common route of infection is via the respiratory tract through inhalation of air born virus, infection via elementary tract is also possible. It may be transmitted to human by contact or ingestion. In man FMD is characterized by fever, salivation and vesiculation of the mucous membranes of the oropharynx and of the skin of the palms, sole fingers and toes. In animals, clinically the disease develops in 2-14 days after infection depending on the virus dose, strain and site of entry. It characterized by lamness, anorexia, pyrexia, salivation, reduced milk production and weight loss. In uncomplicated cases, resolution of infection is usually completed by 14 days after infection. However, mortality may reach 70 in complicated cases, usually from myocarditis which occurs preformently in young animals. Convalescent animals may harbour the FMDV in the pharangeal region. Vaccinated animals exposed to the virus may become persistently infected without showing clinical signs. Either or both two approaches are used to control the disease. The first of these is the use of strict movement controls, exclusion and slaughter policy, employed usually by disease-free countries. The second approach is vaccination, which is used widely by countries in which the disease is endemic such as Egypt. To achieve satisfactory disease control by either or both the two approaches, it is necessary and essentially to require the availability of simple and sensitive laboratory tests for the immunological screening and following up of the imported as well as the susceptible and infected animals, evaluating vaccine potency, appropriate selection of new field virus strains to be incorporated eventually in commercial vaccines, and the development of persistence in both vaccinated animals following infection and imported animals. Because of the progress in the molecular virology and the introduction of new methods, specially PCR, have supplied research laboratories with new alternative for virus identification. Enzyme-linked immunosorbent assay is a very valuable tool for detection and assessment of specific antiviral antibody so ELISA and PCR were the ideal two laboratory diagnostic techniques of choice. The present study aimed to: 1- Study the persistence of FMDV at different intervals post infection among representative samples of sheep, cattle and buffaloes in Upper Egypt (Sohag) by the use of PCR. 2- Study the efficacy of FMDV vaccine in the production of humoral antibody in animals. This study was carried out on 150 apparently healthy animals distributed as follows: - 50 sheep. - 50 cattle. - 50 buffaloes. They were recruited from private and governmental farms in Sohag. All relevant information were obtained for every animal in questionnaire sheet. Probang and serum samples were taken from each animal and subjected to PCR and ELISA techniques respectively.