Introduction to Virology

Nature of Viruses

Viral genome is packaged in protein coat

Virus Genomes

Nature of Viruses

• Viruses need a living cell to survive

• Viral genome is released inside the cytoplasm of the host cell

• Virus genomes are made of DNA or RNA– Not both– Single stranded (ss) OR double stranded (ds)

Why Study Viruses

Why Study Viruses

• Viruses are capable of infecting all forms of life

– Vertebrates, prokaryotes, fungi, algae• Most abundant form of life

– Bacteriophages are extremely abundant– Estimated 1031 tailed bacteriophages

• Excellent molecular biology tools

Viruses And Molecular Biology• Study of viruses small DNA viruses led to discovery of

promoters for eukaryotic RNA polymerases

• Study of cancer producing viruses led to discovery of many cellular oncogenes

• RNA splicing in eukaryotic cells was discovered by studying mRNA from DNA viruses

• Understanding of cellular DNA replication was facilitated by studying phages and DNA viral replication

Major Virology Milestones

Major Virology Milestones

• “Phage” group made significant discoveries/contributions to the field of molecular biology

• Bacteriophages hold promise as antibiotics

• Particularly in antibiotic resistant bacteria

• Immune reaction to phages remains a serious obstacle

• Study of tumor viruses let to a clearer understanding of cancer

Viruses As Vectors

• Viruses can be engineered to carry exogenous genes

• The exogenous genes can be inserted in the host’s genome

•When utilizing a virus to insert genes into a host, we refer to that virus as a Vector Virus

•Vector virus hold promise as therapeutic agents

•Immune response remains an issue

Detection And Measurement of Viruses

•Plaque Forming Assay

•Initially done with bacteriophages and bacteria

Detection And Measurement of Viruses

•Hemagglutination Assay

•Rapid and convenient

Detection And Measurement of Viruses