Epstein Barr Virus Herpes virus group

Cytomegalovirus Herpes virus group

Mumps Virus Paramyxovirus group

Herpes Virus Structure Icosahedral virus

Lipoprotein envelope, derived from the nuclear membrane

Genome: linear, ds DNA

Replicate in the nucleus

Herpes Virus Group

Includes: HSV-1, HSV-2, VZV CMVCMV, EBVEBV HHV-6 and others

Lytic and latent infections

Immortalizing effect (EBV)

EPSTEIN-BARR VIRUS

EPSTEIN-BARR VIRUS EBV has a very limited host range and

tissue tropism defined by the limited cellular expression of its receptor (CD21)CD21).

This receptor is expressed on B lymphocytes Epithelial cells of the oro – and

nasopharynx

Diseases

Infectious Mononucleosis

African Burkitt’s Lymphoma

Nasopharyngeal Carcinoma

EBV-induced lymphoproliferative disease

EPIDEMIOLOGY EBV is transmitted in saliva.

The immunosuppressive potential of malaria has been suggested as a cofactor in progression of latent EBV infection to African Burkitt’s lymphoma.

The restriction of nasopharyngeal carcinoma to certain regions of China has suggested a genetic predisposition.

Transplant patients, AIDS patients are at high risk for Lymphoproliferative disorders initiated by EBV.

B-lymphocytes transformation, by EBV does not need viral genome integration. (Episomal genome)

EBV in saliva

Epithelial cells of oropharynx

B cells proliferation

T cells activation

Liver

Lymph node

Spleen Shedding in saliva

Pharyngitis

Heterophile antibodies

Atypical lymphocytes

swelling

THE LATENT CYCLE

EB nuclear antigen 1(( EBNA-1

Viral promoter( ori P)

EBNA-2

B cell immortalization

Monoclonal antibodies(Heterophile antibodies )

Antibodies to EBNA persist for life.Antibodies to viral capsid antigen (VCA)appear during active

disease.CD8+ T cells are activated against EBNA proteins

Destroy infected B cellsAtypical lymphocytes T cell immunodeficiencies B cell lymphoma

CLINICAL FEATURES Infectious MononucleosisInfectious Mononucleosis (IM)

Fever, malaise, pharyngitis, lymphadenopathy, hepatosplenomegaly.

The disease is rarely fatal.

Heterophile antibody positive.

The classical lymphocytosis associated with IM is due to activation and proliferation of suppressor (CD8+) T cells. These cells appear as atypical lymphocytes (Downey cells).

EBV-induced lymphoproliferative diseaseEBV-induced lymphoproliferative disease

Individuals lacking T-cell immunity are likely to suffer polyclonal leukemia-like B-cell proliferative disease and lymphoma upon EBV infection.

Transplant patients are at high risk for post-transplant lymphoproliferative disorder (PTLD).

African (endemic) Burkitt’s lymphomaAfrican (endemic) Burkitt’s lymphoma

Poorly differentiated monoclonal B-cell lymphoma

jaw and face endemic to children of malarial

regions of Africa. The tumor cells contain chromosomal

translocations that moves the C-myc oncogene to a very active promoter. (Immunoglobulin gene promoter)

Nasopharyngeal carcinoma The tumor is endemic to China The tumor is of epithelial origin.

Oral hairy leukeplakia Mouth lesions An opportunistic presentation in AIDS

patients.

LABORATORY DIAGNOSIS Atypical

lymphocytes, lymphocytosis

Heterophile Antibody Heterophile Antibody

(Paul-Bunnell or Monospot Test)(Paul-Bunnell or Monospot Test) IgM antibody that recognizes the Paul-Bunnell

antigen on sheep and bovine erythrocytes but not guinea pig kidney cells. It is an excellent indication of EBV infection in adults, not children.

Other Serological Tests IgM antibody to VCA, most specific test.

Treatment No vaccine available. Acyclovir is used in treating oral hairy leukoplakia.

CYTOMEGALOVIRUS

DISEASES

Cytomegalic inclusion disease

Heterophile negative mononucleosis

Diseases in the immunocompromised patients

PROPERTIES Icosahedral virus Lipoprotein envelope, derived from the

nuclear membrane Genome: linear, ds DNA Replicate in the nucleus Latent infections Single serotype Humans are the natural hosts Giant cell formation (Cytomegalo)

TRANSMISSION

Oral (saliva) and respiratory routes Transplacental, within the birth canal

and in breast milk Sexual (semen, cervical secretions) Blood transfusion and organ

transplantation More the 80% of adults have antibody

against this virus.

CLINICAL FORMS Normal host

Asymptomatic latent infection Infectious mononucleosis-like syndrome (Heterophile

antibodies- negative). Immunocompromized host (AIDS patients, those

receiving organ transplants or chemotherapy) Pneumonia, hepatitis Severe diarrhea and retinitis in AIDS patients

Congenital infection in utero: Infection of the fetus occurs when a primary infection

happens in a pregnant woman (no virus neutralizing antibodies)

Abortion Stillbirth

Cytomegalic inclusion diseaseCytomegalic inclusion disease

Congenital abnormalities are more common when the fetus is infected during the first trimester of pregnancy.

Includes microcephaly, mental retardation, blindness or deafness.

Hepatosplenomegaly is very common.

LABORATORY DIAGNOSIS

Cell culture with the use of immunofluorescent antibody.

PCR-based assays. Histological staining of

inclusion bodies in giant cells: intranuclear and an intranuclear and an oval “owl’s-eye” oval “owl’s-eye” shapeshape.

Rising IgG antibody titre or single IgM antibody test

TREATMENT Ganciclovir is effective in the treatment of

CMV retinitis and pneumonia in AIDS patients.

Fomiversin is antisense DNA approved for the intraocular treatment of CMV retinitis. It is the first antisense molecule to be approved for the treatment of human disease.

MUMPS VIRUS

VIRUS Paramyxovirus ssRNA, non-

segmented genome Single serotype

TRANSMISSION Humans are the

natural host Respiratory

droplets Peak incidence in

winter

PATHOGENESIS

URT Blood Parotid glands, testes, pancreas and meninges

Lifelong immunity occurs

CLINICAL PICTURE

Incubation period: 18-21 days Prodrome: fever, malaise and anorexia Parotid gland swelling Resolve spontaneously within 1 week Complications Orchitis bilateral

sterility Meningitis

LABORATORY DIAGNOSIS

Virus isolation from saliva, spinal fluid

Rising antibody titre

PREVENTION

Live attenuated vaccine

MMR (Measles, Mumps, Rubella)