Intro rna dna

Adolf Meyer

Demonstrated that Tobacco Mosaic Disease (TMD) was contagious by sap transfer, though he believed the agent was a small bacterium.

Dmitri Ivanovsky

Discovered that the agent causing TMD was “filterable,” passing through filters that trapped bacteria, suggesting a smaller infectious particle.

Martinus Beijerinck

Confirmed Ivanovsky’s findings, proved the agent could reproduce, and named it “virus,” meaning “poisonous fluid.”

Wendell Stanley

Crystallized the Tobacco Mosaic Virus in 1935, showing viruses behave like complex chemicals.

Friedrich Loeffler & Paul Frosch

Discovered the first animal virus (foot-and-mouth disease virus) and demonstrated early viral vaccination principles.

Walter Reed

Proved Yellow Fever was caused by a filterable virus transmitted by mosquitoes

Ellerman & Bang

Showed that avian leukosis in chickens was caused by a virus, the first evidence of a virus causing cancer

Frederick Twort

First observed bacteriophages (viruses that infect bacteria) in 1915

Félix d’Hérelle

Independently discovered bacteriophages in 1917 and named them “bacteria eaters

Edwin Schultz, Steinhardt & Colleagues

Successfully cultured vaccinia virus in tissue explants, pioneering modern virology techniques

Jakob von Fürth & Paul Sturm

Used mice as experimental models for viral propagation, advancing in vivo virology

Woodruff & Goodpasture

Developed viral culture in embryonated chicken eggs, essential for producing vaccines like smallpox and influenza

Virus

A submicroscopic obligate intracellular parasite containing either DNA or RNA, surrounded by a capsid

Virion

A fully assembled, infectious virus particle

Capsid

Protein coat protecting viral nucleic acid

Capsomeres

Protein subunits making up the capsid

Nucleocapsid

Combination of viral genome and capsid

Envelope

Lipid membrane around some viruses, acquired from host cells

Obligate intracellular parasite

Type of parasite of virus requiring living host

Host specificity

Viruses infect only specific host species or cell types.

Naked virus

Virus without an envelope; resistant to drying, heat, and chemicals.

Enveloped virus

Virus with lipid envelope; sensitive to detergents and disinfectants.

Rabies virus

Broad host range example

HIV, which infects CD4+ T cells only

Narrow host range example

Parvoviruses (17–20 nm)

Smallest viruses

Mimiviruses and Pandoraviruses (up to 1 µm)

Largest viruses

Helical viruses

Rod/filament-shaped viruses with capsid arranged spirally (e.g., TMV, rabies, Ebola)

Icosahedral viruses

Spherical viruses with 20 triangular faces (e.g., adenovirus, poliovirus).

Complex viruses

Viruses with additional structures (e.g., bacteriophages, poxviruses).

Baltimore classification

System that classifies viruses into seven groups based on genome type and mRNA replication strategy.

Attachment, penetration, synthesis, assembly and maturation, release

Stages of viral replication

Non-enveloped viruses

are usually released by cell lysis

Enveloped viruses

are commonly released through budding

nucleus

DNA virus replication site

Poxviridae

Exception for DNA replication, replicate entirely in the cytoplasm

cytoplasm

RNA virus replication site

RNA-dependent RNA polymerase (RdRp)

Enzyme required by RNA viruses

Orthomyxoviridae and Bornaviridae

RNA viruses replicating in the nucleus

Virulent phage

Bacteriophage that undergoes the lytic cycle, killing the host

Temperate phage

Bacteriophage that can choose lytic or lysogenic cycles.

Lysogeny

Process where viral DNA integrates into bacterial chromosome as a prophage

Induction

Activation of prophage into lytic cycle (triggered by stress like UV light

Oncovirus

Virus capable of causing cancer by disrupting tumor suppressor proteins

Human papillomavirus

linked to cervicalandotheranogenitalcancers

Epstein-Barr virus (EBV)

associated with Burkitt’s lymphoma and nasopharyngeal carcinoma

Hepatitis B and C viruses (HBV, HCV)

Cause hepatocellular carcinoma.

International Committee on Taxonomy of Viruses (ICTV

International committee that standardizes virus classification.

virales

Order naming suffix

viridae

Family naming suffix

virinae

Subfamily naming suffix

virus

Genus naming suffix