Herpesviridae Family

1. Herpesviridae Family Dr.NehalDraz

2. A good teacher is one who “…does not bid you to enter the house of his wisdom, but rather leads you to the threshold of your mind.”. (Gibran)

3. Introduction • Leading cause of human viral disease, second only to influenza & cold viruses. • Capable of causing overt disease or remaining silent for many years only to be reactivated, e.g. shingles • Derived from the Greek word herpeinmeans tocreep……reflects the creeping or spreading nature of the skin lesions caused by herpes virus.

4. Structure • Large, enveloped DNA viruses • Icosahedralcapsids • DNA replicates in the nucleus of host cells

5. This family includes 8 human pathogens: • Herpes simplex viruses (HSV) types 1 &2 • Varicella Zoster virus (VZV) • Cytomegalo virus (CMV) • Epstein-Barr virus (EBV) • Human Herpes viruses (HHV) types 6,7&8

6. General Characteristics • Most infections are asymptomatic • They remain latent in the host after recovery from primary infection • All herpes viruses cause recurrent infections by reactivation of viral replication • In tissue culture they produce: • Intracellular inclusion bodies • Cytopathic effect: balloning and rounding of infected cells followed by cell death • Some are oncogenic: HSV-2, EBV, and HHV-8 • They can cause severe disease in immunocompromised hosts and neonates

7. Dr Ekta Chourasia, Microbiology

8. Types of Herpesviruses Dr Ekta Chourasia, Microbiology

10. Herpes Simplex Viruses • Extremely wide spread in human population • Establish latency in nerve cells • Reactivation is common • There are two distinct types of HSVs: type 1 &type 2 • Structurally & morphologically indistinguishable • Exhibit sequence gene homology with serological cross-reaction • Can be distinguished by restriction enzyme analysis of viral DNA and mode of transmission

11. Pathogenesis of HSV 1 &2 Sensory ganglia replication Initial infection site Migration through Neuron reactivation Reactivation is through stress stimuli such as UV light, fever, hormonal changes, surgical trauma to the neuron latency Antibodies do not prvent reactivation HSV-1: trigeminal ganglia HSV-2: sacral ganglia

12. Diseases caused by HSV-1 1- Oropharyngeal infections: • Acute gingivostomatitis: occurs in early childhood • Fever, • painful vesicular lesions ; on gums, lips & oral mucosa, these vesicles may rupture leaving a red based ulcer which • may be 2ry infected with candidaalbicans forming white coat • Herpes labialis (fever blisters or cold sores) • Milder recurrent form • Crops of vesicles at the mucocutaneous junction of lips or nose

13. Herpes Labialis Acute herpetic ginfivostomatitis

14. 2- Herpetic Keratoconjunctivitis: • Corneal ulcers and lesions of conjunctival epithelium • Recurrence takes the appearance of dendritic ulcer or vesicles on the eye lids • Recurrent keratitis may lead to permanent scarring ending with blindness

15. Keratitis Vesicles around eye lid

16. 3- Encephalitis • Rare • Involves temporal lobe with high mortality 4- Herpetic Whitlow: • Fingers herpes infection • In health care workers e.g. dentists & nurses 5- Eczema Herpeticum: • Involves known eczematous areas with bacterial superinfection 6- Disseminated infection: Fatal esophagitis or pneumonia in immunocompromised patients

17. Herpetic Withlow Eczema Herpeticum

18. Diseases caused by HSV-2 1- Genital herpes: • Sexually transmitted • Vesiculoulcerative lesions of penis in males and cervix, vulva, vagina, & perineum of females 2- aseptic meningitis: Self limited 3- Neonatal Herpes: Aquired in utero,during, or after birth Severe in the newborn so, pregnant females with recurrent herpes should deliver by CS

19. Neonatal Herpes

21. Laboratory Diagnosis • Specimen: Vesicular fluid- Corneal scrapping 1- Direct Virus Demonstration: a) L/M: • Tzanck smear – from the base of vesicles, 1% aq. soln. of toluidine blue ‘O’ shows multinucleated giant cells with faceted nuclei & homogenously stained ‘ground glass’ chromatin (Tzanck cells) • Giemsa stained smear – intranuclearCowdry type A inclusion bodies

22. Tzanck smear intranuclearCowdry type A inclusion bodies

23. B) Direct Immunofluorescence: • Cell scrappings from lesions are stained with monoclonal antibodies conjugated with a fluorescence dye. Viral inclusion bodies appear in UV microscope as a bright green intranuclear particles • C) PCR: for detection of viral DNA in CSF

24. 2- Viral Isolation: tissue culture: human diploid fibroblasts, human amnion, human embryonic kidney: CPC (syncytium formation) seen in 24-48 hrs. • 3) Serology: useful in the diagnosis of primary infection, Ab (IgM) detection by ELISA, NT or CFT.

25. Treatment • Inhibits viral DNA polymerase enzyme • topical, oral, or IV Acyclovir Doesn’t affect latency

26. Varicella –Zoster Virus (VZV) Causes 2 major diseases • Varicella (chicken pox): primary infection usually in childhood • Zoster ( shingles): reactivation of an earlier varicella

27. Varicella (Chicken Pox) • Mild, highly contagious disease chiefly affecting children • Mode of transmission: - airborne droplets and direct contact from varicella patients - Vesicular fluid of Zoster patients can be the source of Varicella in susceptible children

28. Pathogenesis: • VZV infects the mucosa of the upper respiratory tract • Multiplies in the regional LNs • Primary viremia and spread to liver and spleen • Secondary viremia follows with viral spread to the skin • Typical rash occurs • VZV remains latent in the dorsal root ganglia for life

29. Clinical Picture: • Incubation period: 10-21 days • Symptoms: mild fever & rash • Rash: first appears on the trunk, then face and limbs • Flat macules become papules then vesicles • Followed by crust formation • The crust is often shed off and heals without scarring • Cropping is a characteristic feature of varicella rash: fresh vesicles appear in crops, so that all stages of macules, papules, vesicles & crusts are seen at the same time • More severe in adults

31. Complications • 1- pneumonia especially in adults, may be fatal • 2- rarely: fulminant encephalitis, which may be a manifestation of Reye’s syndrome that occurs as a consequence of salicylates intake during infection

32. Congenital Varicella Syndrome & Neonatal Varicella • Primary maternal infection during the 1st trimester may lead to congenital varicella syndrome ( serious & fatal): skin lesions, hypoplasia of limbs, chorioretinitis & CNS defects • Primary maternal infection near the time of birth can lead to widely disseminated infection in the new born with mortality rate of 35% • If rash began a week or more before delivery, maternal Abs transferred via placenta – baby gets the infection but escapes clinical disease

33. Zoster (shingles) • Sporadic disease in adults or immunocompromised patients • Results from reactivation of latent VZV • Rash similar to varicella but limited to a nerve distribution to the skin innervated by a dorsal root ganglion (dermatom)

34. Complications: • If affecting the eye via trigeminal nerve: keratitis, conjunctivitis & iritis • It can affect the brain via the cranial nerve leading to Bell’s palsy • Post Herpetic neuralgia: Very painful, Likely due to nerve damage from zoster outbreak, Lasts for months after zoster resolves & Does not respond to antiviral treatment

35. Laboratory Diagnosis • Specimen: Vesicular lesions smears 1- Direct Virus Demonstration: a) L/M: Tzanck smear – from the base of vesicles, 1% aq. soln. of toluidine blue ‘O’ shows multinucleated giant cells with faceted nuclei & homogenously stained ‘ground glass’ chromatin (Tzanck cells)

36. B) Direct Immunofluorescence: • Cell scrappings from lesions are stained with monoclonal antibodies conjugated with a fluorescence dye. Viral inclusion bodies appear in UV microscope as a bright green intranuclear particles • C) PCR: for detection of viral DNA 2- serology: • Specific VZV Abs using CFT, Nt, or ELISA

37. Treatment • Inhibits viral DNA polymerase enzyme • Used in immunocompromised patients with chicken pox, zoster, or varicella complicated with pneumonia, keratitis, & neonatal Varicella Acyclovir Doesn’t affect latency

38. Prevention 1- Active immunization 2- Passive immunization • Live attenuated varicella vaccine Single dose, age: 1-12 yrs • Varicella zoster immunoglobulins (VZIG) Given to: • Immunocompromised children exposed to infection • Mothers infected near term(before delivery) and their infants ( immediately after delivery)

39. Epstein-Barr Virus (EBV) • Infects more than 95% of human poulation • Primary infection: acute infectious mononucleosis, a self limiting disease • It is an oncogenic virus associated with human malignancies

40. Mode of transmition • Requires intimate contact with the saliva of an infected person ( kissing disease) • Doesn’t normally occur through air or blood

41. pathogenesis • Replication in nasopharyngeal epithelium • Spreads to salivary glands and oropharyngeal lymphoid tissue • Further replication results in viremia, with subsequent infection of reticuloendothelial system; liver, spleen & B- lymphocytes • Host immune response includes CTLs (cytotoxic T-lymphocytes); characteristic atypical lymphocytes found in peripheral blood

42. CTLs destroy EBV-infected B-cells reducing their number • Followed by latency in B-lymphocytes & oropharyngeal epithelial cells • In some cases EBV DNA becomes integrated with the host chromosome giving the infected cell the ability to proliferate indefinitely resulting in malignancy

44. Disease 1- infectious mononucleosus: • Fever,malaise, lymphadenopathy, pharyngitis & hepatosplenomegaly with or without jaundice • May be rash • The severity depends on age ( younger milder) 2- EBV-associated malignancies: - Burkitt’s lymphoma in Africans - Nasopharyngeal carcinoma in Asians

45. Nasopharyngeal carcinoma in Asia Burkitt’s lymphoma in Africa

46. Laboratory diagnosis Blood picture: absolute lymphocytosis with atypical lymphocytes ( Downey cells) Specific Diagnosis: • Specimen: saliva,peripheral blood & lymphoid tissue 1- Direct Virus Demonstration: a) Direct Immunofluorescence: Cell scrappings from lesions are stained with monoclonal antibodies conjugated with a fluorescence dye. Viral inclusion bodies appear in UV microscope as a bright green intranuclear particles b) PCR and nucleic acid hybridization: for detection of viral DNA, most sensitive

47. Paul Bunnel test Downey cells monospot test

48. 2- serology: • a) detection of non-specific heterophil Abs: • patients with acute infectious mononucleosis develop transient non-specific Abs that agglutinate sheep RBCs. These are detected by Paul Bunnel or monospot tests • b) detection of specific Abs: by ELISA, indirect IF: • IgM to viral capsid Ag ( VCA-IgM)= recent infection followed by IgG to viral capsid Ag ( VCA-IgG) that remains for life • different Abs against other EBV Ags appear later in different stages of the disease No antiviral drugs or vaccines are available

49. Cytomegalovirus (CMV) • A prevalent virus pathogen • Asymptomatic infection in healthy adults • Several high-risk groups including organ transplant patients & HIV-patients are at risk of developing life- & sight-threatening CMV disease • CMV may be also devastating or even fatal to fetuses or newborns when aquired congenitally

50. Modes of transmission • 1- close contact with most body fluids ( saliva, urine, vaginal secretions & semen) • 2- transplacental & perinatal transmission (2ry to exposure to infected birth canal or breast feeding) • 3- sexual • 4- Blood transfusion • 5- organ transplantation