RETROVIRUSES

➤Have an RNA core ➤Use RNA to make DNA (backwards

transcription) ➤Has enzyme reverse transcriptase ➤Mutate more easily and quickly (no

proofreading!) ➤Difficult to find treatment

➤Ex. HIV

HIV FACTS

➤ Human Immunodeficiency Virus

➤ Officially recognized in 1981- possibly 1970s?

➤ Attacks Helper T cells (coordinate the immune system)

➤ Retrovirus

➤ Lysogenic

HIV STATS

➤ Has killed more than 25 million people ➤ Estimated at least 33 million people currently HIV

positive ➤ Most recent estimates show that in 2006 in the U.S.,

56,300 new HIV infections occurred ➤ Young people (under age 25) account for 50% of all

new HIV infections worldwide

HIV GLOBALLY

➤ About 65% in sub-Saharan Africa

STRUCTURE OF HIV➤ Lipid envelope

➤ Retrovirus (RNA core)

➤ Reverse transcriptase enzyme

➤ Mutates quickly; hard to treat

HIV STRUCTURE

HIV- HOW IT’S SPREAD

➤ “HIV is spread by sexual contact with an infected person, by sharing needles and/or syringes (primarily for drug injection) with someone who is infected, or, less commonly (and now very rarely in countries where blood is screened for HIV antibodies), through transfusions of infected blood or blood clotting factors. Babies born to HIV-infected women may become infected before or during birth or through breast-feeding after birth.”

--Center for Disease Control

HIV- SYMPTOMS

➤ You can’t rely on symptoms for HIV recognition

➤ Only way to know you are infected is by getting tested

➤ Symptoms may only appear as the disease progresses- they are specific to opportunistic infections

CLINICAL DISEASE CYCLE➤ Phase I= Asymptomatic

➤ CD4 count >500 cells per μL

➤ Flu-like symptoms or no symptoms

➤ Phase II= Symptomatic

➤ CD4 count= 200 cells per μL

➤ Weight loss, fatigue, diarrhea, opportunistic infections, etc.

➤ Phase III= Late Symptomatic

➤ CD4 count <200 cells per μL

➤ AIDS

➤ Pneumocystis pneumonia

HIV - TREATMENTS

➤ Symptoms of opportunistic infections are treated

➤ Viral replication may be slowed by drugs targeting retroviruses and their enzymes (HAART: Highly Active Anti-Retroviral Therapy)

➤ Fusion inhibitors, reverse transcriptase inhibitors, protease inhibitors

BENEFICIAL USES OF VIRUSES

➤Vaccines ➤Antibacterial agent- Bacteriophages can

infect and destroy bacteria ➤Biotechnology/genetic engineering- Gene

therapy; replace affected DNA

GENE THERAPY

SCID (SEVERE COMBINED IMMUNODEFICIENCY)

GENE THERAPY CASES