Transcript Slide 1
Foot and Mouth Disease Virus (Aphthovirus) Nereli Isabel G. Agripa 4MB Virology Order: Picornavirales Family: Picornaviridae Genus: Aphthovirus • Foot and mouth Disease – Aphthovirus – Cloven-hoofed animals • Hand, foot and mouth Disease – Coxsackie A virus and Enterovirus 71 – Infants and children I. Virology A. Structure • capsid – – • • icosahedral 4 polypeptides with (pseudo) T=3 packing. Diameter = 27-30nm genome -tightly packed into the capsid Figure 1: An electron micrograph of negatively-stained picornavirus particles. Source: http://www.microbiologybytes.com/virolo gy/3035pics/Picornagif.html I. Virology B. Genome • one s/s (+)sense RNA molecule of between 7.2kb (HRV14) to 8.5kb • Picornaviruses: – Infectious genomic RNA – 5' end = long untranslated region – 3' end = shorter untranslated region – 5' UTR contains the IRES – The rest of the genome encodes a single 'polyprotein’ – Both ends of the genome are modified, I. Virology C. Replication Figure 2: Diagram of Picornaviridae replication Source: http://www.microbiologybytes.com/virology/3035pics/Picorna2.gif Replication I. Virology D. Serotypes –O –A –C – SAT-1 – SAT-2 – SAT-3 – Asia-1 II. Signs and Symptoms • rise in body temperature for 2 to 3 days. • Vesicles that rupture and discharge clear or cloudy fluid, leaving raw, eroded areas surrounded by ragged fragments of loose tissue. • sticky, foamy, stringy saliva. • Reduced consumption of feed = painful tongue and mouth lesions. • Lameness with reluctance to move. • Abortions. • Low milk production (dairy cows). • Myocarditis (inflammation of the muscular walls of the heart) and death, especially in newborn animals. III. Mechanism A. Pathogenesis - Inhalation of airborne virus / infection via alimentary tract or skin lesions Primary replication – pharynx Bloodstream 3-5 days febrile viraemia Secondary infection B. Transmission – – – – Direct or indirect contact Animate vectors Inanimate vectors Airborne, especially temperate zones IV. Diagnosis Incubation period – 2-14 days A. Clinical diagnosis B. Differential diagnosis • Clinically indistinguishable: – Vesicular stomatitis – Swine vesicular disease – Vesicular exanthema of swine • Other differential diagnosis: – – – – – – – Rinderpest Mucosal disease Infectious bovine rhinotracheitis Bluetongue Bovine mammillitis Bovine papular stomatitis Bovine viral diarrhoea C. Laboratory diagnosis – ELISA – Complement fixation test – Virus isolation V. Prevention • Sanitary prophylaxis – border animal movement control and surveillance – Slaughter of infected, recovered, and FMD-susceptible contact animals – Disinfection of premises and all infected material – Destruction of cadavers, litter, and susceptible animal products in the infected area – Quarantine measures • Medical prophylaxis – Inactivated virus vaccine containing an adjuvant. VI. Epidemiology • One of the most contagious animal diseases • Low mortality rate in adult animals, • Often high mortality in young = myocarditis VII. References http://www.cdc.gov/ncidod/dvrd/revb/enterovirus/hfhf.htm http://www.oie.int/eng/maladies/fiches/A_A010.HTM http://www.microbiologybytes.com/virology/Picornaviruses.html