• I - dDNA
• II - single stranded, + sense DNA
• III - dRNA
• IV - single stranded, + sense RNA
• V - single stranded, - sense RNA
• VI - single stranded, + sense RT RNA
• VII - RT dDNA

Viral surface proteins and entry mechanisms

(influenza and HIV)

• In influenza, HA1/2/3/5/6/7/9/10 attaches to sialic acids on oligosaccharides (cleaved by NA) to allow endocytosis of vesicle (pH dependent - pump of protons into endosome required for HA conformational change to expose fusion peptide)
• In HIV, env receptor - gp120 associates with CD4 receptor, allows exposure of gp41 and binding to CCR5 or CXCR4. Subsequently, the core is uncoated to create PIC, the nuclear import of which is mediated by microtubules

• RNA polymerase (negative strand must have virion RNA pol)
• Retoviruses need reverse transcriptase and integrase

Transformation by DNA viruses

(tumour and virus type)

• Proteins within EBV (EBNA-1, EBNA-3C and LMP-1) can transform B lymphocytes to form Burkitts lymphoma (B lymphocytes in germinal centre) and lymphoepithelioma in the nasophyrnx
• Papilloma virus - causes warts through keratinocyte proliferation (expression of viral oncogenes E6 and E7 and inactivation of p53 and pRb tumour suppressors) - can cause cervical cancer
• HBV chronic infection associated with hepatocellular carcinoma 

Endogenous anti-virals

(types, function and inhibition)

• Type I interferons (α/β) are expressed through the recognition of PAMPs by PRR, and are released into the extracellular matrix to trigger release of interferon stimulated genes (ISGs)
• ISGs include MXA (prevents nuclear viral import), MX1 (blocks transcription), OAS and RNase L (cleavage of viral RNA), PKR (blocks translation), viperin (blocks influenza release by preventing lipid raft formation)
• NS1 released from viruses sequesters viral DNA, prevents RIG-1 activation and prevents host gene expression

• Plasma IgG 
• sIgA - dimeric IgA is present in mucous secretions of saliva, sweat, colostrum and GU, GI and respiratory tracts
• Produced by plasma cells, binds to pIgR for release in external secretion, or to Ig-R on basolateral surface of lamina propria epithelial cells to allow secretion of secretory component 

• Sandfly takes blood meal and injects promastigote into skin
• Promastigote are phagocytosed by macrophages or mononuclear phagocytic cells
• Promastigotes transform into amastigotes
• Amastigotes multiply in phagocytes, lyse the cells, and infect other macrophages in various tissues
•  Sandfly takes blood meal and ingests amastigote infected macrophage
• Amastigotes transform into promastigotes in gut
• Division in gut and migration to proboscis

• Tsetse fly takes blood meal and injects metacyclic trypomastigotes 
• Injected metacyclic trypomastigotes tranform into bloodstream trypomastigotes, which are carried to other sites
• Trypomastigotes multiply by binary fission in body fluids (blood, lymph and CSF)
• Trypomastigotes in blood are taken in blood meal by tsetse fly
• Bloodstream trypomastigotes transform into procyclic trypmastigotes in midgut and multiply by binary fission
• Procyclic trypmastigotes leave midgut and transform into epimastigotes
• Epimastigotes multiply in salivary gland and transform into metacyclic trypomastigotes

• Mosquito takes blood meal and injects sporozoites
• Sporozoites infect liver cells and mature into schizonts which rupture and release merozoites
• Merozoites infect red blood cells and form ring stage trophozoites, which mature into schizonts - in turn rupturing and releasing merozoites. Some parasites differentiate into gametocytes 
• Gametocytes (microgametocyte males and macrogametocyte females) are ingested by Anopheles mosquito and fuse to form zygote
• Zygote becomes motile ookinetes to invade midgut and develop into oocysts 
• Oocysts grow, rupture and release sporozoites which reach the mosquito salivary gland 

Types of vaccine

(types and examples)

• Live attenuated - viral: MMR, flu, chicken pox, Sabin polio. Bacterial: BCG, typhoid, epidemic typhus
• Immunologically related - vaccinia (cowpox as vaccine for smallpox)
• Killed whole vaccines - cholera, pertussis
• Subunit vaccines: Hep B, HPV, Salmonella typhi
• Inactivated exotoxin - tetanus toxin, botulinum toxin 
• Vectored vaccine by adenovirus or pox virus containing genetic material encoding antigens