Defense III Flashcards
1
Q
vaccination history
A
- Edward Jenner in 1798 developed the first vaccine
- He observed that milkmaids who had previously caught cowpox did not catch smallpox because they had already made antibodies/t/b cells that could recognize virus
- He inoculated cowpox and demonstrated that it protected against inoculated smallpox but didn’t understand the mechanism
2
Q
Types of adaptive immunity
A
o Active: create own antibodies
1. Artificial: injected or received a drug, vaccine, inoculation, modified virus, proteins from virus
2. Natural: body mounts immunological response, memory cells, create own antibodies
o Passive: receive antibodies
1. Artificial: serum, where give antibodies that recognize virus to patient
2. Natural: breast feeding delivers antibodies
3
Q
Vaccine types
A
- Protein subunit: injected with a component of viral protein
- Virus like particle: contain something of virus but not genetic material
- DNA or RNA based vaccine with genetic material of virus
- Viral vectors: replicating or non-replicating that are no longer infectious
- Inactivated: “kill” render virus unable to function so recognized by system
- Live attenuated: copies of virus made weaker so can’t harm us but body can recognize and create antibodies
4
Q
MRNA vaccine works by
A
- Lipid coat with genetic material of virus enters host
- Produce proteins then present them to MHC to be used to mount an immunological response
5
Q
Viruses
A
- Small infectious agents, obligate intracellular parasite, not a “life” b/c cant exist on own
- can infect all types of life forms like animals, plants, eubacteria and archaea
- Can be very diverse
o the simplest virus is composed of a nucleic acid core (RNA or DNA with + or - strand) surrounded by a coat of proteins (capsid)
o more advanced viruses may have a phospholipid envelope they stole
6
Q
sources of infection
A
- During our evolution the risk of viral infections increased dramatically
o many viruses that infect humans are derived from domesticated animals
o Problems of waste disposal and hygiene
o Pathogens have evolved in relationship to the host and to the vectors they rely on for their survival and fitness
7
Q
retroviruses
A
- Single stranded RNA virus
- With an envelope
- Contains the info to create an integrase enzyme to integrate its own DNA into the host’s genome to create more virions
- Infects t helper cell
8
Q
virion
A
- Envelope: composed of lipids and glycoprotein (env). Important for: Protection & Infection
- RNA: contain two identical single-stranded RNA molecules 7–10 kb in length, codes for virion proteins:
- most common are Gag, Pol, Env,
- more are integrase , Tat and others
9
Q
HIV background
A
- HIV (human immunodeficiency virus) infection has now spread to every country in the world.
- Approximately 40 million people are currently living with HIV infection
- Approx. 39 million have died from this disease.
- In the United States, approximately 1 million people are currently infected.
- Every 10 minutes one person in the US is infected with HIV
10
Q
HIV process
A
- HIV recognizes the CD4 receptor on T-helper lymphocytes using his surface glycoprotein gp120
- Once HIV binds to the CD4 receptor gp120 undergoes a conformational change that results in the binding with additional receptors in the host cell
- The viral glycoprotein gp41 is then able to mediate the fusion of the viral envelope with the cell membrane which allows RNA to enter into cell
- The viral reverse transcriptase converts the viral RNA into DNA, which enters the nucleus and is inserted into the cellular genome by the viral integrase
- Viral DNA can remain latent for years while replicating the whole time unseen
- After the latent phase, the virus is activated to undergo lytic cycle killing the host cell and t helper cells
11
Q
Antigenic variation in HIV
A
- HIV has a great **genetic heterogeneity **
o caused by the error prone nature of reverse transcription - HIV being a highly mutable virus
o exhibits frequent antigenic variations, nucleotide variations, cell tropism, growth characteristics and cytopathology - Differences can be identified between:
o sequential isolates from the same person
o between **isolates obtained from different sites **of the same person at the same time - highly intergenic so error prone by reverse transcriptase make the surface proteins look somewhat different so we cant make vaccines to attack them cause they change so fast
12
Q
These characteristics contribute to the virulence and effective propagation of the virus
A
- It is not possible to develop antibodies that can recognize the virus for a prolonged time
- The virus can enter the body as infected cells, in which the virus is protected because cant be recognized by antibodies inside cells
- Virus readily establishes lifelong latent infection hiding from antibodies while replicating
- This tendency to accumulate mutations has contributed to the fast evolution of the virus
13
Q
HIV modes of transmission
A
- Sexual contact - In the vast majority of cases transmission is by sexual contact
- Parenteral - by blood transfusion or blood product transfusion – numbers are decreasing
- Sharing of unsterilized needles or syringes contaminated with blood from an infected person
- Occupational risks - accidental needle sticks in the healthcare setting
- Organ transplantation (donors are tested for HIV to minimize this risk but latency could cause false negatives)
14
Q
Vertical transmission
A
- Women can transmit HIV to the fetus during pregnancy or birth, when infected maternal cells enter the baby’s circulation
- 30% of children born to infected mothers have the acquired infection unless virus is treated by antiviral drugs before pregnancy
- In nursing mothers’ transmission can occur through breast milk
- In mothers taking medications, the risk is the less than 2% mostly due to birthing so need to do a C section so no blood crossover from mother during birth
15
Q
Mortality/Morbidity of HIV
A
- The course of HIV infection is characterized primarily by latency
- Profound immune suppression eventually develops, and the illness appears to be almost uniformly lethal
- Progression from HIV infection to AIDS occurs 8-10 years after infection without antiretroviral treatment
- Since the introduction of highly active antiretroviral therapy (HAART) and prophylaxis against opportunistic pathogens, death rates from AIDS have declined significantly.
