Togaviruses fackrel@uwindsor.ca toga.ppt
Toga Viruses Structure Classification Multiplication Epidemiology Control
Togaviridiae Rubivirus-rubella Alphavirus- Equine Encephalitis, Sindbis Pestivirus- animal pathogens - bovine viral diarrhea, hog cholera
Rubella German Measles (first diagnosed by German doctors) Three day Measles
Rubella: Structure enveloped icosahedral ss RNA sense 40-80 nm 30 nm core hemaglutinin peplomers
Rubella: Classification Family Togaviridae single serotype three structural polypeptides
Rubella: Multiplication RNA is capped and polyadenylated serves as mRNA -> nonstructural proteins sense RNA -> antisense RNA Antisense RNA template for progeny RNA antisense RNA--> mRNA -> structural proteins mature at intracytoplasmic membranes
Postnatal rash lymphadenopathy low grade fever Congenital stillbirth spontaneous abortion birth defects
Congential Rubella Ocular- cataracts, retinitis, glucoma ,microphthalmaia Heart defects- patent ductus arteriosis Deafness- cochelar deafness, central auditory imperception CNS- mental retardation, encephalitis, microcephaly Other- hepatitis, pneumonitis
Rubella: Pathogenesis respiratory secretions -direct contact, droplet multiplies in cells of respiratory system extends to lymph nodes, spleen
Rubella: Epidemiology worldwide vaccines licenced 1969 no new epidemics incidence ~ 100 /year
interferon cell mediate immunity neutralizing antibodies hemagglutinin inhibiting antibodies asymptomatic reinfection possible
Rubella: Diagnosis Clinical manifestations- rash, lymphadenopathy Isolate virus respiratory tract Detect Rubella IgM
isolate virus - urine, CSF, blood maternal circulating IgG- lasts 6 months Detect fetal or neonate IgM
Rubella: Control live attentuated rubella vaccine - mumps-measles-rubella combination
subcutaneous 15 months of age asymptomatic in children mild symptoms in adults
Rubella: Control Strategies 10-20% young women not immunized - college students
- health care personnel
- military personnel
- after childbirth, miscarriage or abortion
Alphavirus
Alphaviruses are arthropod borne (arboviruses)
Alphavirus: Structure icosahedral 40-50 nm enveloped attachment glycoprotein ss RNA, sense, monopartite
Alphavirus: Classification common capsid antigenic sites 26 antigenic types
Alphavirus: Multiplication RNA is capped and polyadenylated serves as mRNA -> nonstructural proteins sense RNA -> antisense RNA Antisense RNA template for progeny RNA antisense RNA--> mRNA -> structural proteins mature at intracytoplasmic membranes
Subgenomic mRNA 3’ one-third of antisense strand -> mRNA mRNA -> structural proteins
Alphavirus: Clinical manifestations Encephalitis viruses - fever, malaise, headache and/or encephalitis
Arthritis viruses - fever, rash, arthralgia, arthritis
Alphavirus: Epidemiology mosquito-vertebrate-mosquito cycles geographically restricted epizootics- Venezuelan equine enchephalitis urban epidemics- chikungunya virus seasonal
Alphavirus: Diagnosis clincal manifestations known exposure isolate virus detect IgM
Alphavirus: Control reduce mosquito populations vaccinate vertebrate hosts- horses vaccine humans at high risk of exposure
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