17. Characteristics of herpesviruses, groups, epidemiological features.

Question 1

Virus info?

Answer 1

Herpes virales order

Herpes viridae family: extra info

• Simplexvirus (11 sp.)
• Varicellovirus (17 sp.)
• Mardivirus (4 sp.)
• Iltovirus (2 sp.)
• Scutavirus (1 sp.)
• Betaherpesvirinae subfamily
• Cytomegalovirus (4 sp.)
• Muromegalovirus (2 sp.)
• Proboscivirus (1 sp.)
• Roseolovirus (2 sp.)
• Gammaherpesvirinae subfamily
• Lymphocryptovirus (8 sp.)
• Rhadinovirus (7 sp.)
• Macavirus (9 sp.)
• Percavirus (3 sp.)
• Alloherpesviridae family: Cyprini-, Ictaluri-, Salmoni-, Batrachovirus (Fish, frog herpesviruses, 11 sp.)
• Malacoherpesviridae family: Ostreavirus (oyster herpesvirus)

Question 2

Virus size and resistance?

Answer 2

Herpesvirus

• 120-200nm, dsDNA, icosahedral, enveloped
• more than 20 structural proteins,
• 10-12 of them in the envelope - can be detected (marker),
• immunosuppressive

Resistance:

• (poor antigens) weak, 60C,
• disinfectants destroy within minutes,
• sensitive to detergents
• cannot give long lasting immunity,
• so good to give immunisation frequently

Question 3

Stenoxen?

Answer 3

Stenoxen:

• But aujeszky disease, Malignant catarrhal fever, turkey herpes, monkey herpes B-zoonotic
• All mammalians are susceptible, except for primates (human, monkey)
• Strong CPE, differences within subfamilies:
• Alpha: broad spectrum, short replication cycle < 24 hr
• Beta: narrow spectrum, longer replication > 24 hr
• Gamma: narrow spectrum, B and T cell tumor, immunosuppression

Question 4

Latency persisting infections?

Answer 4

Latency, persisting infections:

• Hide genome into nucleus of certain cells as episome, causing lifelong infection
• Alpha (neuron - encephalitis),
• beta (gland, lymphoid),
• gamma (lymphoid cell latency)
• Reactivation - after immunosuppressive effect, lifelong carrier
• Latent phase: virus is not shed or produced
• Antigenicity: weak antigens (enveloped glycoproteins), vaccine protection usually for a few months, crossreactions with genera, even cross-protection
• Marker vaccines: deletion mutants, point-mutations (missense), risk of recombination (marker rescue), GMO
• vaccines (virus is able to multiple, but not cause disease)
• DIVA = differentiation of infected and vaccinated animals - use of marker vaccine
• Dual system: vaccine and detection system

Question 5

Diagnostics, treatment and prevention?

Answer 5

Diagnostics:

• isolation, ELISA, latent infections - co-cultivation,
• PCR (most use in viral detection,
• incase of active and latent infection),
• NA hybirdization, serology - ELISA (discriminative), VN

Treatment:

• nucleoside analogues - acycloguanozin (in humans),
• not registered and expensive in veterinary use

Prevention:

• hygiene,
• immunisation,
• eradication