Foot and Mouth Disease Virus ( Aphthovirus )

1. Foot and Mouth Disease Virus (Aphthovirus) Nereli Isabel G. Agripa 4MB Virology

2. Order: Picornavirales Family: Picornaviridae Genus: Aphthovirus

3. Foot and mouth Disease • Aphthovirus • Cloven-hoofed animals • Hand, foot and mouth Disease • Coxsackie A virus and Enterovirus 71 • Infants and children

4. 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/virology/3035pics/Picornagif.html

5. 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 untranslatedregion • 5' UTR contains theIRES • The rest of the genome encodes a single 'polyprotein’ • Both ends of the genome are modified,

6. I. Virology C. Replication Figure 2: Diagram of Picornaviridae replication Source: http://www.microbiologybytes.com/virology/3035pics/Picorna2.gif

7. Replication

8. I. Virology D. Serotypes • O • A • C • SAT-1 • SAT-2 • SAT-3 • Asia-1

9. 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.

10. III. Mechanism • Pathogenesis • Inhalation of airborne virus / infection via alimentary tract or skin lesions • Primary replication – pharynx • Bloodstream • 3-5 days febrile viraemia • Secondary infection • Transmission • Direct or indirect contact • Animate vectors • Inanimate vectors • Airborne, especially temperate zones

11. IV. Diagnosis Incubation period – 2-14 days • Clinical diagnosis • 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 papularstomatitis • Bovine viral diarrhoea C. Laboratory diagnosis • ELISA • Complement fixation test • Virus isolation

12. 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.

13. VI. Epidemiology • One of the most contagious animal diseases • Low mortality rate in adult animals, • Often high mortality in young = myocarditis

14. 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