Which Human Diseases Are Caused By Viruses? Viruses cause diseases in the many organisms that they infect. This slide lists some of the more well-known infectious diseases of humans caused by DNA and RNA viruses. Viruses also cause significant problems in animals and plants. Some viruses, referred to as “tumor viruses,” also can cause cancer. The cancer-causing abilities of some tumor viruses have been demonstrated only in animals. However, there is growing evidence that certain viruses cause specific types of human cancers. For example, some types of papillomavirus, a DNA virus, have been identified as a cause of cervical cancer. HTLV-1, a retrovirus, causes a type of adult leukemia. References: Campbell, N.E., & Reece, J.B. (2002). Biology (6th ed.). San Francisco: Benjamin Cummings. Flint, S.J., Enquist, L.W., Krug, R.M., Racaniello, V.R., and Skalka, A.M. (2000). Principles of Virology: Molecular Biology, Pathogenesis, and Control . ASM Press.
reproduce at a fast rate, but only in living host cells
can mutate / evolve
Nonliving characteristics of viruses
are acellular ( no cytoplasm or organelles )
not autonomous: carry out no metabolism on their own (i.e. viruses don't grow and divide )
replication is fully dependent on the host cell's metabolic machinery ; viral components are synthesized and assembled within the infected host cell
Viral Size Viruses are usually much smaller than bacteria and are submicroscopic. Most range in size from 5 to 300 nm . Thus viruses can infect even other microorganisms. Animal RNA Virus Animal DNA Virus Bacteriophage
Usually derived from host cell membranes by a proces s called buddin g.
Electron Micrograph of HIV Budding from a T4-Lymphocyte Virus Obtaining Its Envelope from Host Cell Membrane by Budding
Chicken Pox DNA VIRUS varicella-zoster virus (VZV)
Polio RNA Virus Nonparalytic polio causes symptoms that mimic the flu. Sore throat, fatigue, nausea, diarrhea, a fever, or vomiting. Most cases of nonparalytic polio clear up in a number of days, but a some people go on to develop meningitis, a condition in which the lining of the brain is infected. When a person develops paralytic polio, destroys nerves that control muscles. The infection may be fatal if the brain and respiratory organs become affected. Polio is a serious condition that causes paralysis in about 1% of those infected (paralytic polio).
Herpes DNA Virus Herpes Simplex 1 and herpes simplex 2. The sores are sometimes accompanied by other symptoms such as: headache, fever, and other flu-like symptoms pain, itching, tingling, or tenderness around the genitals painful urination, swollen tender points in the groin and lower abdomen
Genital Warts HPV – human papillomavirus DNA Virus GARDASIL VACCINE