Introduction to Herpes Viruses
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Herpes Viruses
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VP26 Assembly in HSV-1 Capsid
Herpes Virus Outline
Herpes have a Unique Structure
- Iscadeltahedral protein capsid
- lipid envelope with glycoproteins
Human Herpesvirus Subfamilies
Infect both vertebrate and non vertebrate
Bovine Herpes
Herpesvirinae
- Human herpesvirus 1 -HHV1
Herpes simplex type 1-HSV1
- Human Herpesvirus 2 -HHV2
Herpes simplex type 2 -HSV2
Animations of HSV
- RNA Transcription in productive infection
- Encapsidation and Release
Click here to view Dr. Ed. Wagner, superb series of animations on HSV on the internet
Herpes simplex virus
Herpes simplex virus
Isolated from a patient with shingles
Herpesvirinae
- Human Herpesvirus 5 -HHV5
Cytomegalovirus
Herpesvirinae
- Human Herpesvirus 6 -HHV6
Very restricted host range
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Varicellavirus
- genus in herpesvirus family
- human herpesvirus 3 (HHV3)
Multiplication
Genes replicated in specific order
- Early genes
- enzymes for replicating viral DNA
Occurs in host cell nucleus
Latent Infections
- ALL herpes viruses can establish latent infections. The viral genome may become incorporated into the host DNA or remain extrachromosomal
- Latent viruses can be reactivated by stress, menstruation or uv light
- Reactivation may be asymptomatic or lead to mild or severe disease.
Diagnosis
- Isolation of virus by tissue culture
- herpevirinae cause cytopathic effects
- intranuclear fluorescence of scrapings using fluorescent antibodies
CMV retinitis is diagnosed clinically
Prevention of Herpesvirus
- Vaccines
- VZV vaccine being licensed
- HSV1, HSV2, & CMV vaccines being developed
- Passive immunization
- pooled immunoglobulin
- hyperimmune globulin
Anti-herpesvirus drugs
- Idoxuridine- herpetic keratitis
- Trifuridine-herpetic keratitis
- Vidarabine - wide range of applications
- Acylovir-wide range of applications
Herpes Simplex Viruses
Epidemiology of Herpes Simplex
- HSV1 is transmitted by kissing or other contact with saliva
- HSV2 is spread by sexual contact
- HSV2 is spread nosocomially
Mucocutaneous infections caused by Herpes simplex
- Herpes simplex labialis (cold sores)
- Whitlows- health care workers
- Herpes gladiatorum- wrestlers
Herpes simplex type 1
- Herpes labialis.
- cold sores or fever blisters. text: page 569.
- 2-12 day incubation period.
- gingivostomatitis -- vesicles rupture.
- latent virus in ganglia -- Herpetic keratoconjunctivitis -- ulcers can be identified by fluorescein staining.
Herpes simplex
Herpes simplex
Herpes simplex
Transmission: HSV1
- Transmitted by direct contact such as kissing or fondling; very common with young children.
- Good personal hygiene does curtail the transmission.
Treatment HSV1
- The first drugs were used to treat conjunctivitis and keratitis
- Iododeoxyuridine
- trifluridine
- adenine arabinoside
- acyclovir
Treatment HSV1
- Iododeoxyuridine: direct application to the cornea
- Trifluridine, Keratitis: direct application
- Adenine arabinoside: direct application to the cornea. Intravenously injected, it reduces mortality from herpes encephalitis.
- Acyclovir: is now the drug of choice, is the least toxic. Can be used topically, orally and intravenously.
Genital Herpes HSV2
- primary infection: vulva, vagina, cervix. glans penis, prepuce or penile shaft.
- fever, malaise, anorexia, bilateral inguinal adenopathy.
- sexually transmitted - highest rate among young adults.
- Patients on immunosuppressive drugs
Neonatal Herpes Simplex
- infants acquire the virus passing through the birth canal.
- disseminated herpes - newborns; premature infants susceptible
Herpes Simplex Encephalitis
Treatment HSV2
- Acyclovir does not cure the initial infection, but because it prevents the attachment of released virus from an infected cell, it ameliorates the disease. With aggressive treatment eventually the viruses disappear. It is not an effective cure for the latent stage.
Herpes simplex infection of egg membranes
Herpes Intranuclear inclusions
Herpes simplex Syncytia
Ctyopathic effect