DNA Viruses IWSDNA病毒分类.COLLIN.EDU.pptVIP

DNA Viruses Viral replication implies: attachment, penetration, and DNA lytic or lysogenic cycles General Properties: NA DNA Single or Double stranded Glycosylated and/or Methylated Cytosine, Uracil, Thymine Circular or Linear Unique purine and/or pyrimidine bases Bound protein molecules General Properties: Capsid Protomers - Capsomeres - Capsid Protein Coat Organization gives the virus form Icosahedral Triangular face with hexon 12 corners with penton Helical Protomers not grouped in capsomeres Bound together to form a ribbon which folds Complex General Properties: Envelope Lies outside the capsid Made up of lipids, proteins, CH20 Contains antigens from host virus Enveloped or Nonenveloped (naked) +/- Spikes Glycoprotein projections of envelope Functions Enzymatic Adsorption Hemagglutin Viral Replication Cycle Adsorption (Attachment): viral protein + host cell receptor Penetration Uncoating: cytoplasm of host using proteolytic enzymes Replication of NA (DNA) Early Transcription (ds DNA is needed, ss- ds) Early Translation (mRNA- enzymes for viral DNA) Late Transcription (ds DNA used) Late Translation (mRNA- proteins for capsid) Assembly: NA + capsid Maturation Enveloped: cell membrane Non-enveloped: naked, accumulated in cell - inclusions Complex: multilayered membrane Release: via cell lysis Viral Pathogenicity Contributing Factors Ability to enter cell Ability to grow in cell Ability to combat host defenses Ability to produce damage Cell Lysis via hypersensitivity reactions (II, IV) Production of toxic substances Cell transformation Metabolism and cellular products: Turn “on” genes Structural: Nuclear or Cytoplasmic inclusions ds DNA Viruses HERPESVIRIDAE ds DNA Icosahedral Asymmetrical tegument between capsid and envelope Enveloped Glycoprotein spikes 8 human serotypes Latent, recurring infections Human Herpesvirus 1 2 HSV1,2 or Herpes Simplex HSV1: Associated with oro-facial lesions HSV2: Associated with genital lesions Direct contact Subclinical Vessicles