epstein barr virus herpes virus group cytomegalovirus herpes virus group mumps virusparamyxovirus...
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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)