Herpes viruses

Properties of herpes viruses

• Large family of DNA viruses,

having an icosahedral protein

capsid and a lipid envelop

• Enveloped Icosahedral double

stranded DNA viruses

• Spikes of viral glycoproteins

project from the envelop

• It includes

Herpes Simplex virus

Varicella-Zoster virus

Ebstein-Barr virus

Cytomegalovirus

Properties of herpes viruses

. Stages:

Primary infection (skin and mucous membran) Exposure to the virus for the first time, by direct contact

Involves the mucous membranes of the mouth, skin, lips, nose, eyes (HSV-1) and genital tract (HSV-2)

Clinically: vesicles rupture to form crusts that heals without scaring.

Latency (in a sensory ganglia)

Reactivation asymptomatic shedding of the virus at site innervated by

the affected neurons (Fever, UV, stress, immunosuppression)

Herpes Simplex Viruses

HSV is spread by contact, as the virus is shed in saliva,

tears, genital and other secretions.

HSV 2 is transmitted sexually or to newborn during birth

Cell ballooning and Multinucleated giant cell formation

Acidophilic intranuclear inclusion bodies

Vesicular lesions change to shallow ulcers. Heal without

scarring.

Generally HSV-1 causes infection above the belt and

HSV-2 below the belt

HSV1: Associated with oro-facial lesions

HSV2: Associated with genital lesions

Reactivation (stress, UV, fever).

HSV-1

Young child

Gingivostomatitis

Herpes Labialis (cold sore)

Ocular Herpes (KCS)

Encephalitis

pneumonia

Latent infections in trigeminal ganglia

Treatment: Acyclovir and Foscarnet

Diagnosis

Diagnosis is based on the clinical findings

Definitive diagnosis is important in serious cases

Isolation of virus on tissue culture

Detection of the HSV in vesicles fluid by EM

Detection of viral DNA by PCR

Detection of viral antigens by IF or ELISA

Serological diagnosis to detect IgM

Varicella- Zoster Virus

The virus is thought to gain entry via the respiratory tract

Primary infection results in varicella (chickenpox) in

children

Reactivation result in Zoster form in adult

Diagnosis: EM, culture, serology for IgM, PCR

Treatment: Acyclovir, nucleoside analog of Guanosine. Binds to DNA polymerase after it incorporated into host DNA

Chickenpox (Varicella) Primary infection

Age: Children 4:10 years

21 day incubation

Direct or droplet

Severe complications in adults, perinatal, or immunocompromisedindividuals

Evolves from papules to vesicles, pustules and finally crusts

Starts on the trunk and spreads to the limbs and face

Shingles (Zoster)

Usually in old age

Reactivation of VZV

Associated with

immunosuppression

Dermatome of sensory

ganglion

Painful vesicular eruption, unilateral and confined to one dermatome (thoracic or lumbar)

Cytomegalovirus

Transmission may occur in utero, perinatally or postnatally.during which infectious virions appear in the urine and thesaliva.

Perinatal infection is acquired mainly through infected genital

secretions, or breast milk.

Postnatal infection mainly occurs through saliva. Sexual

transmission may occur as well as through blood and blood

products and transplanted organ.

Ganciclovir used in treatment

Cytomegalovirus

Congenital infection - may result in cytomegalic inclusion disease

disease (growth retardation, microcephaly, hepatosplenomegaly)

Infection in normal individual - usually asymptomatic- infectious

mononucleosis may develop which consists of fever,

lymphadenopathy, and splenomegaly.

Immunocompromised patients severe CMV disease such aspneumonitis, retinitis, colitis, and encephalopathy.

Epstein-Barr Virus (EBV) infects primarily B cells

The virus is transmitted by contact with saliva, in

preschool children , adolescents

Diseases:

1.Infectious Mononucleosis

Fever, sore throat, skin rash and cervical lymphadenopathy

2. Burkitt's lymphoma

3. Nasopharyngeal carcinoma

EBV attacks B cells polyclonal activation

heterophilantibody and atypical lymphocytes

Diagnosis

increased TLC with absolute

lymphocytosis, and atypical

lymphocytes

Detection of EBV genome

PCR or DNA hybridization.

Detection of heterophil

antibodies that agglutinate

sheep RBCs by Monospot

"slide" or Paul Bunnel test

"tube".

Detection of EBV specific

antibodies: