Genome Naked, icosahedron, (+) sense ss RNA, non- segmented Infection Type Lytic Infection route Fecal-oral High risk Mainly children < 5 years of age *Humans = only natural host Attachment VP1 = virus' "anti-receptor" (forms a pore for RNA to pass into the cytoplasm) CD155 = host's "virus receptor" H (hemagglutinin) = anti-receptor SA (sialic acid) = virus receptor Genome Entry Only the genome enters the cell Genome replication Poliovirus Ch. 5-6 -Occurs in the cytoplasm -VPg serves as a primer to make the RNA strand but cleaved off before translation -Cap-independent translation using IRES - recruits factors (ITAF) to allow for ribosome Influenza A Ch. 7-9 Enveloped (plasma memb. of cell), pleomorphic, (-) sense RNA, segmented Persistent Inhalation of virus particle in air Transferring virus particles from surfaces onto the mucous membrane surfaces Younger (no acquire immunity) and older (higher death rates) Humans = accidental host (Pigs = mixing vessel) H1N1; H1N2; H3N2 The virus enters the cell in an endosome, genome released to cytoplasm/nucleus 1. Tryptase Clara cleaves H to reveal fusion peptide (before binding to SA) 2. pH-dependent change in endosome allows H to unfold so fusion peptide inserts into the endosome membrane for fusion -In the nucleus -uses already packaged polymerase proteins to transcribe (-) RNA to make mRNA -Cap stealing (as a primer to provide 3' HIV Ch. 10-12 Retrovirus; enveloped (matrix under); spherical to pleomorphic; Diploid: 2 identical (+) sense ss RNA, non-segmented Latent Sexual contact Mother-to-infant Blood transfusion/organ transplant Intravenous drug use Occupational exposure (hospital) CD4 = virus receptor Gp120 = anti-receptor *Co-receptor: CXCR4 (CD4 T cells) or CCR5 (CD4 T cells and monocytes) The virus envelope fuses to cell memb., releasing genome into cytoplasm/nucleus *HIV gp120 binds to CD4, triggers conformational change in gp120 > change in gp41 -> fusion peptide inserted into cell membrane > env. Fuses ad core of the virus particle enters the cytoplasm -Reverse transcriptase enzyme activity in the capsid in cytoplasm ( SSRNA -> ssDNA -> dsDNA) > into nucleus) *RT uses tRNA as a primer -Integrase integrates viral DNA into
Assembly VPO, VP1, VP3 assemble to form subunit > 3 subunits form capsomere -> 20 capsomeres form pro-capsid > genome inserted Egress Maturation Immature (VP0, VP1, VP3) Mature (VP1, VP2, VP3, VP4) = infectious Fate of cell Lysed when virus replication is complete Symptoms Abortive Polio (>95% cases, mild, completely recovered) Non-paralytic (1-2%, local inflammatory response, self-limiting infection of meninges) assembly -Protease that damages protein associated w/ 5' cap of cellular mRNA Viroprotein disrupt the plasma membrane so the poliovirus is released when host cell lyses OH group) and cellular mRNA is destroyed -Incomplete (+) RNA: mRNA for protein synthesis; needs 5' cap -Complete (+) RNA: template to replicate genome; no need for 5' cap H/N inserted into cell's plasma memb. New genomic (-) RNA coated with NP and RDRP associates to form RNPs M moves into nucleus and associate with RNPs RNPs directed out of nucleus and assemble with other proteins at plasma memb. *No