Microbiology Lect 24 Flashcards
What responds to a pathogen when your body sees it again?
-Naturally acquired adaptive immunity
-Artificially acquired adaptive immunity: immunization
-Passive or active
Immunization
Immunization is the process by which the immune system becomes artificially fortified against a pathogen
Passive immunization
-Administration of preformed antibodies, immunity is artificially acquired
Active immunization
-Protective immunity is induced (usually through vaccination)
Traditional types of vaccines
-Whole organism vaccines:
-Inactivated: pathogens are grown under controlled conditions, then killed as a means to reduce infectivity, preventing infection from the vaccine
-Ex: polio, rabies
-Attenuated: live but avirulent
-Purified macromolecules (including toxoids)
-Recombinant: Genes encoding for antigen are inserted into non-virulent host
-Ex: put into yeast, then yeast produces the antigen, until we purify the antigen and use it as a vaccine
What is a toxoid?
A chemically modified toxin that is no longer harmful but still has the antigen determinant
Human papillomavirus (HPV)
-Caused by many different viruses in the family Papillomaviridae
-dsDNA viruses
-Often host and tissue specific (rare transmission between diff. species
-Really common sexually transmitted disease
~80% of unvaccinated people will become infected with HPV during lifetime
-Some strains cause genital warts
-A few HPV strainsa re responsible for most cases of cervical cancer in women (5,000 deaths per year in US)
HeLa immortalized cells
-One of the most commonly used human cell lines is called HeLa
-These cells are HPV-18 infected human cells
-In 1951, a 31-year-old mother named Henrietta Lacks, developed cervical cancer from which she died
-Her cancerous cells were taken without permission and formed the HeLa cell line
HPV vaccine
-Vaccine based on HPV viral protein L1 (Gardasil and Cervarix)
-Recombinant-antigen vaccine (yeast cells genetically engineered to produce viral protein)
-Nearly 100% effective (against HPV types 18 and 18)
-Approved by FDA in 2006 (girls) and 2009 (boys)
Smallpox
-Variola major virus, dsDNA virus
-Cause of smallpox
-no asymptomatic individuals
Smallpox general facts
-Kills 30%-40% of infected individuals
-In the 18th century, smallpox disfigured or killed 10% of the world’s population
-Destroys kidneys, heart, brain
-Transmitted by saliva, contaminated clothing, bedding
-Humans only natural reservoir of smallpox
Societal Impacts of Smallpox in the Americas
-Smallpox killed millions of Aztecs (25% of the population) when Cortes arrived in Mexico on a ship containing individuals infected with smallpox
-Killed 60% of Incans in Peru after invasion by Pisarro, leading to downfall of Incan empire
-British soldiers in 18th century Americas tries to use smallpox as a biological weapon, giving Native Americans blankets from infected individuals
Why was smallpox well suited for eradication?
-WHO instituted smallpox eradication program in 1967
-No asymptomatic carriers
-Easy to identify
-Only humans can get it, so no reservoir
Variolation
-Traditional method of immunizing patients against smallpox by infecting with substance from the pustules of patients with a mild form of the disease
-Started in 11th century China
-Ingrafting common in Europe (1600s-1700s)
Cowpox
-Edward Jenner, 1789, infected a boy (James Phipps) with cowpox sore
-At this time, smallpox killed ~10% of the populations
-Reinoculated with deadly smallpox 20 times of the next 25 years
-By 1800, 130,000 people were vaccinated against smallpox
