HSV I

Question 1

HSV

Answer 1

• Herpes Simplex virus genus of the Herpesviridae family
• Two Types - 1 and 2!
• linear, ds DNA enveloped
• numerous strains

Question 2

HSV Structure

Answer 2

Question 3

Herpes Simplex Viruses Genomic Organization

Answer 3

• 150 kb in length
• Can encode up to 70 polypeptide

1. a - genes (immediate early genes): encode 5 regulatory proteins (a -0, 4, 22, 27, 47), latency associated transcript (LAT1)-antisense to a -0 gene
2. b - genes (early genes): encode DNA binding proteins, DNA polymerase, and thymidine kinase
3. g - genes (late genes): encode structural proteins (glycoproteins)

Question 4

HSV Replication

Answer 4

• DNA released in the cytoplasm
• DNA migrates to the nucleus
• mRNA (transcription) synthesis takes place in the nucleus by using host RNA polymerase
• nuclear membrane
• mRNA transported to the cytoplasm
• virus replication involves regulatory proteins
• New viral proteins made and migrate to nucleus
• Genomic DNA (replication) synthesis takes place in the nucleus by using viral DNA polymerase

Question 5

HSV 1 vs HSV 2 Infection Sites

Answer 5

• HSV 1 above umbilicus
• HSV 2 below umbilicus

Question 6

HSV 1 Transmission

Answer 6

•primarily by direct contact

Question 7

HSV 1 Incubation

Answer 7

•Incubation period: 7-10 days

Question 8

HSV 1 is acute, latent or both?

Answer 8

• Acute and latent infection
• Primarily asymptomatic

Question 9

HSV 1 site of primary infection?

Answer 9

• Gingivostomatitis – primary infection l most common in children 1-6 years, fever, oral blisters on buccal mucosa, tongue, gums vesicles which ulcerate 7-10 day duration
• Labialis (cold sores) - reactivation l vesicles at mucocutaneous junction of lips recurrent (latent) vesicles ulcerate, painful

Question 10

Where does reactivated HSV 1 show up?

Answer 10

•Reactivated HSV is at near or same site of primary infection

Question 11

HSV 1 Keratoconjunctivitis

Answer 11

•corneal ulceration, recurrent, blindness (one of the major causes of blindness in the U.S)

Question 12

HSV 1 Encephalitis

Answer 12

•Temporal lobe, high mortality

Question 13

HSV 1 Eczema herpaticum

Answer 13

• mild or fulminant
• Injured skin, burn patients, ulceration

Question 14

HSV 1 Herpetic Whitlow

Answer 14

•tips of finger and nails, occupational

Question 15

HSV 2 Transmission

Answer 15

•sexually transmitted

Question 16

HSV 2 Incubation

Answer 16

• 2-12 days
• 80% of the patients develop recurrent infection within 12 months

Question 17

HSV 2 Vulvovaginitis

Answer 17

• mucous membranes and skin of labia, lower vagina, cervix
• Lesions become ulcerated, painful, fever

Question 18

HSV 2 Progenitalis

Answer 18

•ulcers on penis and/or on skin in groin or perianal area

Question 19

HSV 2 Asceptic Meningitis

Answer 19

•self limiting

Question 20

HSV 2 Neonatal Herpes

Answer 20

• 30-60% transmission rate with primary infection, lower rates in recurrent infection
• Contracted during delivery
• 6-10% babies develop neonatal herpes
• Widespread organ involvement
• High mortality - more than 60%
• Neurologic sequelae in survivors

Question 21

HSV Latency

Answer 21

• All Herpes viruses establish latent infections
• Site of latency and features of reactivation disease are different for each virus
• During latent infection, certain viral proteins are produced, but no complete viral particles.
• The genome is present as a circular extrachromosomal element in the nucleus of the infected cell.
• Latent stage is not affected by treatment.

Question 22

HSV Reactivation

Answer 22

• Reactivation - same site as primary infection
• DNA resides in ganglia (trigeminal root ganglion, sacral AREA, but dorsal root ganglion)
• Reactivation: trauma, fever, sunlight, excitement, emotional stress (EXAMS)

Question 23

How does latent herpes reach peripheral sites?

Answer 23

Question 24

HSV Diagnosis

Answer 24

• isolate virus in cell culture
• stain biopsy material (immunofluorescence)
• DNA detection by PCR (mainly in latency)

Question 25

HSV Treatment

Answer 25

* Most effective drug is acyclovir * Foscarnet is active against acyclovir-resistant HSV * eye infections (topical), acyclovir, idoxuridine (IUDR), adenine arabinoside, trifluorothymidine

Question 26

HSV Encephalitis Treatment

Answer 26

•Intravenous -Acyclovir, Vidarabine

Question 27

HSV Genital herpes Treatment

Answer 27

•Acyclovir (oral and topical), Vidarabine

Question 28

HSV Neonatail Treatment

Answer 28

•Vidarabine, Acyclovir

Question 29

HSV Treatment

Answer 29

* Avoid contact with lesions * Safe sex practices, condom usage