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: 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:

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