DNA enveloped viruses, herpes viruses types of herpes viruses

1. DNA envelopedViruses
(herpes viruses)
Zahra Rafi
Lecturer Microbiology, FLS

2. HerpesViruses
 Consist of 6 important human pathogens.
1. HSV 1,2
2. Varicella-zoster virus
3. CMV
4. Epstein-barrVirus
5. Human herpes virus 8

3. Structure
 Icosahedral, lipoprotein envelope, linear double stranded
genome, no polymerase, large(120-200 nm ), 2nd largest viruses.

4. Replication:
infection:
 Inside nucleus, get envelope from budding of nuclear membrane
 Tegument: present between envelope and capsid, contains
regulatory proteins.
 Latent infections, acute infections followed by latency, during
immunodeficiency it reactivates.
 E.g, HSV-1,same as of acute but acute and latency is different in
VZ-V

5. How latency
occurs in HSV
andCMV
 Shortly after HSV infects neurons, LATS (latency associated
transcripts , non-coding regulatory RNA) form, that
suppresses viral replication.
 CAUSE: unknow, but fever chills, and sunlight can cause this.

6. Continued….
 CMV form microRNA, they stop replication of mRNA, also they
code a protein that inhibits apoptosis of infected cells, so they
attain latency

7. Clinical
Symptoms
 Vesicular Rash: formed by HSV-1,2, andVZV. Formed in both,
start and reactivation.
 Primary infection is more severe, not caused by CMV and EBV
 Multinucleated giant cells: formed by four HSV’s , HSV1,2, CMV,
VZV, detected byTzank smear, taken by genital vesicle.
 https://universe84a.com/collection/tzanck-smear-test-postive/

8. Types of HSV
 3 types of HSV exist
1. Alpha herpes (HSV 1,VZV)
2. Beta Herpes( CMV’s , human HV6)
3. Gamma herpes ( EBV, human HV8)
VZV EBV

9. Alpha herpes
beta herpes
gamma herpes
 Infects epithelial cells and neurons
 Infect and attain latency in tissues
 Infect and attain latency in lymphoid
cells
Some herpes viruses
may also cause cancer

10. Epstein-barr
virus
 Cause Burkitt’s lymphoma
 Nasopharyngeal carcinoma
 Can also cause cancer in animals
 Symptoms and transmission:
 Sexual transmission (HSV2 ), saliva (HSV 1), fever, rash (starting
from trunk towards head) in series o f conversions of papules to
vesicles to pustules to crusts
 They are mild in children and severe in adult.

11. VZV
 Causes shingles, vesicles along sensory nerve
 pain during and after vesicles
 Post therapeutic neuralgia
 Use vaccine for prevention
 No vaccine for HSV

12. CMV
 Genital/congenital abnormalities
 Pneumonia, is common in children
 Cause: seizures, microcephaly, jaundice,
 Treatment: ganciclovir, no vaccine, shedding in urine.