microbio redacted

Tetracycline is an antibiotic that inhibits bacterial protein synthesis by binding the 30S

ribosomal subunit. Although it is efective against many bacteria, it does not treat measles, a

Baltimore Group V (-ssRNA) virus. What best explains why?

It does not have it’s own ribosome, it uses the host ribosome

Amantadine is an antiviral drug that was historically used to treat influenza A infections. Many

circulating influenza A strains are now resistant due to a specific mutation in the viral genome

(S31N). What best explains how this mutation creates resistance to amantadine?

-This will alter the conformation of M2, preventing amantadine from binding. Low pH in endocyotic vesicle will be able to occur and uncoating + membrane fusion will occur.

Pertussis (whooping cough) is a bacterial respiratory infection caused by Bordetella pertussis. It

has an estimated R₀ of 12–17 and a case fatality rate generally below 1%, although disease can be

more severe in young infants. Ebola hemorrhagic fever is caused by an RNA virus and has an

estimated R₀ of 1.5–2.5, and an average case fatality rate of about 50%.

Although Ebola is far more lethal than pertussis, the herd immunity threshold for pertussis is

higher. What best explains this difference?

the R0 (rate of transmission) is lower, and herd immunity is not based on virulence, but rather transmissibility. Overall, if there is less spreading then less people need to be vaccinated to prevent transmission and this value will be lower.

subunit vaccine

isolated surface antigens (HPV, shingles, anthrax, cholera, tetanus)

toxoid vaccine

inactivated toxin

attenuated vaccine

live but the virulence is removed (chicken pox, flu, polio, yellow fever)

inactivated vaccine

killed (Hep-A, flu, polio, rabies)

mRNA vaccine

provides the body with instructions to make pathogen proteins (B and T cell in muscle, T in APC in lymph node) - Sars vaccine

key advantages live attenuated vaccines

strong, long lasting, mimic natural infection, fewer doses needed, more complete immune response

humoral immune response

type of adaptive response, B cells from plasma cells and make antibodies that neutralize pathogens and mark them for elimination (to bone marrow).

innate immune response

present from birth (skin, stomach acid, inflammation)

adpative immune response

contains humoral and mediated, antigen-specific and generates memory

cell-mediated immune response

type of adaptive response. T-cells coordinate immune response and kill infected cells directly (CTLs go to infection site)

PFU/ml equation

plaques * dilution factor (positive)/ amount plated (in ml)

SARS-CoV-2

-group IV (+) ssRNA

-translation right away

-endocytosis

-uses RNA dep RNA pol and host ribosome

Influenza

-group V (-) ssRNA

-endocytosis

-uses RNA dep RNA pol and host ribosome

HIV

-group VI (+) ssRNA (2 copies)

-retrovirus

-extra capsid

-no endocytosis

-uses reverse transcriptase to make ssDNA + host RNA pol then

HPV

-group 1 (dsDNA)

-replication by host DNA pol, then host RNA pol for transcription

-has separate lysosome for uncoating

You look under the microscope and count physical viral particles (you actually can’t because

they are too small but pretend that you can). In the same viral stock you see 25% more viruses/ml

as pfu/ml calculated in (9.1). Both numbers are accurate. Explain how they can both be true.

pfu/ml is the number of plaque forming units. virus/ml is all virus particles (infectious or not). Virus particles might not form plaques if the phage has an empty capsid, or it isn’t able to attach to release it’s DNA properly. This results in a higher virus/ml number than pfu/ml.