Viruses
What are the 7 groups of viruses by Baltimore?
Double stranded DNA
Single stranded DNA
Double stranded RNA
(+) Single-stranded RNA
(-) Single stranded RNA
RNA retroviruses
DNA pararetroviruses
What's the difference between pathogenicity and virulence?
Virulence is how “bad” a virus is, pathogenicity is how contagious it is.
Compare and contrast Salk and Sabin vaccines.
Salk vaccines used inactivated polio, injected into patients, and the vaccine had immune cells produce IgG to fight. Sabin used attenuated viruses, given orally, and the vaccine had immune cells created IgA and IgG to fight.
What are the three portals of entry?
Mouth: Food-borne pathogens
Respiratory tract: Airborne pathogens
3. Parental Route: Agents transmitted by vectors
What are some antifungal drugs?
Amphotericin B: For severe, systemic fungal infection
2. Fluconazole (Diflucan) and Itraconazole (Sporanox)
Targets fungal version of cholesterol.
How do bacteriophages replicate?
Host recognition
Attachment
Genome entry
Assembly of virions
Exit and transmission
Father of Epidemiology? What was his initial study?
John Snow. Advocated for removal of water pumps to get rid of cholera. He wanted to do this because he made a map of infection/deaths, and he saw that many of them were around the pump.
What is CRISPR-Cas 9? What do we use it for, and what are some ethical concerns?
Bacterial defense system against bacteriophage.
It’s for gene editing. Some ethical concerns are that designer babies could be in our future, or for malicious things like eugenics. Also can help cure sickle cell anemia.
What are the 2 main bacterial toxins?
Exotoxins: Proteins produced by various types of bacteria ; kill host cells and obtains their nutrients
2. Endotoxins: Part of lipopolysaccharide of Gram- bacteria ; can hyperactivate host immune systems to harmful levels.
How do microbes protect themselves against antibiotics?
Change receptor for drug
Bind to drug and inactivate it (penicillinase)
Change target site (changes ribosome structure)
Change metabolic pathway
MDR pump – multi-drug resistance pump
What is the difference between the lytic and lysogenetic cycle in viruses?
Lytic Cycle: Phage quickly replicates, killing host cell
Lysogenic Cycle: Is quiescent.
Integrated into cell chromosome, as a prophage
Can reactivate to become lytic
What does LD50 and ID50 mean?
LD50 is lethal dosage, and deals with the pathogenicity. ID50 is an infectious dose, deals with virulence.
Compare animal and plant viruses and entry strategies.
Animal viruses need a receptor, plant viruses need physical contact to transmit.
Receptor binding is what determines host range. Interaction between host and virus.
What are the 5 main ways bacteria trick the immune system?
Molecular mimicry
Altering cytokine profiles
Stopping programmed host cell death
Interfering with autophagy
Autophagy is a universal innate defense mechanism to fight intracellular pathogens
Redirecting ubiquitylation signals
MHC I and II present antigens on host cell
Surfaces to helper T-cells. Some viral E3
Ligases can ubiquitylate the MHC molecules,
marking them for destruction via
endosomal pathways.
Other E3 ligases can ubiquitylate MHC I molecules while in the endoplasmic reticulum, leading to their destruction before being placed on the cell surface.
What are 4 main antiviral drugs?
Oseltamivir (Tamiflu): Treats influenza, inhibits neuraminidase to prevent viral spread
Acyclovir (Zovirax) and Valacyclovir (Valtrex): Treats herpes simplex, chickenpox, and shingles. Interrupts viral replication by mimicking DNA building blocks.
Zidovudine (Retrovir): Treats HIV; inhibits reverse transcriptase, blocking viral RNA to DNA conversion
4. Sofosbuvir (Sovaldi): Treats chronic Hepatitis-C (with other drugs); inhibits RNA polymerase to stop viral replication
What are the 3 bacterial defenses against host immune system?
Genetic resistance: Altered receptor proteins
Restriction endonucleases: Cleave viral DNA lacking methylation
CRISPR: Integration of phage DNA sequences
Clustered regularly interspaced short palindromic repeats ; a bacterial immune system of sorts
What is the MMWR report?
The Morbidity and Mortality Weekly Report (MMWR) is the official epidemiological science periodical published by the U.S. Centers for Disease Control and Prevention (CDC).
What are animal and plant defenses against disease?
Animal and Plant Host Defenses
Genetic resistance: Continually experience mutations
Immune system: Innate and Adaptive immunity (Interferons and antibodies respectively).
RNA interference (RNAi): Widespread among eukaryotes and archaea
What are the 9 categories of microbial exotoxins?
Plasma membrane disruption
Cytoskeleton alterations
Protein synthesis disruption
Cell cycle disruption
Signal transduction disruption
Cell-cell adherence
Vesicle traffic
Exocytosis
Superantigens
What are the 5 modes of antibiotics?
Inhibition of cell wall synthesis
Cell wall is weakened when cell is growing
EX. penicillin and cephalosporins
Inhibition of protein synthesis
Binding to 70S ribosome
EX. Erythromycin, streptomycin
Increase permeability of plasma membrane
Can have high toxicity in humans
Inhibit synthesis of RNA/DNA
Can be very toxic
Inhibition of metabolic pathways
Low toxicity because of the absence of this pathway in humans
What is the HIV replication cycle?
1. HIV binds to CD4 and CCR5 receptor on T-Helper cell
2. HIV and T-Helper membranes fuse
3. Reverse transcriptase converts viral RNA into DNA. DNA is sent to nucleus of the T-Helper cell
4. Integrase inserts viral DNA into DNA of T-Helper (establishes life long infection)
5. HIV proteins are made
6. Virion is assembled in the cell membrane of the T-Helper cell.
7. New HIV buds out of the T-Helper cell. Protease cuts up long chains of HIV protein to help make more HIV.
What are the 6 transmitters of disease?
Direct: Close association between infected and potential host
Indirect: Spread by fomites
Droplet: Transmission via airborne droplets
Vehicle: Transmission by an inanimate reservoir (food, water, air)
Vectors: Transmit disease by 2 general methods
Mechanical: Arthropod carriers pathogen on feet
Biological: Reproduces in vector (like malaria)
Nosocomial: Acquired as a result of a hospital stay. Affect 5-15% of all hospital patients.
What is the Herpes replication cycle?
Envelope proteins bind to alternative receptor molecules on host cell surface.
Microtubular scaffold transports the intact virions to the nucleus, where DNA is injected.
DNA circularizes for transcription–can express mRNA for proteins for infection, or encodes LAT proteins to maintain latency.
Assembly occurs at the nuclear membrane.
Cells are released from cell via exocytosis
Rapid release of virions destroys cells, causing the characteristic sores.
How are virulence genes found? What are they?
Virulence genes can be found on these islands in the chromosome, on plasmids, or on phage genomes.
Contain clusters of virulence genes with specific functions.
Originally inherited through horizontal transmission
Compare and contrast the use of antibiotics in people and farm animals.
Antibiotics are used to treat illness in people, to prevent infections during surgeries, for those with AIDS to prevent any infections, and are prescription regulated. and in farm animals they’re used to make them grow bigger, prevent diseases in high-density environments, promotes feeding efficiency.