VAB study guide questions

Streptococcus pneumoniae

Causes Pneumococcal pneumonia or Pneumococcal Disease

Cell structure of Streptococcus pneumoniae

polysaccharide capsule

Primary site of infection for Streptococcus pneumoniae

nasopharynx (top part of throat)

Secondary sites of infection of Streptococcus pneumoniae

Can spread to lungs, blood, ear, sinuses, and meninges

Corynebacterium diphtheriae

Causes diptheria

Mode of transmission for Corynebacterium diphtheriae

Respiratory droplets and direct contact with someone who is infected

How does C. diphtheriae acquire the ability to produce diphtheria toxin?

lysogenic conversion - bacteriophage inserts its DNA carrying the TOX gene into the bacterial chromosome

B subunit of C. diphtheriae

binds to the host cell receptor, triggering uptake via receptor-mediated endocytosis inside a vesicle. Acidification of the vesicle allows the B subunit to form a pore, releasing the A subunit into the cytoplasm.

A subunit of C. diphtheriae

A subunit halts host protein synthesis, causing the cell to undergo apoptosis. 

Clostridium tetani

Tetanus

Oxygen requirement for Clostridium tetani

It is anaerobic; These grow only without oxygen

Is Clostridium tetani communicable between humans

no

Primary modes of communication for Clostridium tetani

It enters through wounds like cuts, puncture wounds, umbilical stumps, lacerations, burns, and bites.

host protein targeted by tetanospasmin and how it leads to paralysis/lockjaw

• Synaptobrevin- a protein that helps nerve cells release chemical messengers called neurotransmitters

• Tetanospasmin breaks down synaptobrevin

• This prevents the release of 2 inhibitory neurotransmitters, GABA and Glycine, which normally tell muscles to relax; without those signals, muscles keep contracting and can’t relax properly 

• This causes spastic paralysis-muscles become stiff and contract uncontrollably

Bordetella pertussis

Whooping cough

function of three key outer surface structures in Bordetella pertussis

Fimbriae and filamentous hemagglutinin play a role in attachment to host cells, while pertactin is an outer membrane protein that allows it to resist neutrophil-mediated clearance.

(Bordetella pertussis) how the AB-type pertussis toxin alters intracellular signaling (cAMP pathways) following endocytosis into host cells. 

It adds ADP-ribose from NAD+ onto inhibitory G proteins to inactivate them, which allows cAMP signaling to occur uninhibitedly. 

Neisseria meningitidis

Meningococcal / Meningococcal disease

primary mucosal colonization site of Neisseria meningitidis and clinical manifestation. 

Nasopharyngeal mucosa. can enter the bloodstream and meninges, causing fever, headache, and stiff neck.

(Neisseria meningitidis) Which surface structures serve as the target antigens for vaccines against Serogroups A, C, W, Y?

capsular polysaccharides found on the outer surface. targeted by MenACWY vaccines to help the immune system recognize and fight the bacteria.

Describe the primary capsular component of Haemophilus influenzae type b (Hib), a target molecule in the current vaccine.

Polyribosylribitol-phosphate polysaccharide (PRP) capsule

Primary invasive disease of Haemophilus influenzae type Hb (Hib)

Meningitis

High fever, severe headache, altered mental status

High risk age demographics for Haemophilus influenzae type b (Hib)

5 and under

65 and older

Mycobacterium tuberculosis

Tuberculosis/TB

What unique chemical component in the Mycobacterium tuberculosis cell envelope renders it acid-fast?

Waxy lipids (Mycolic Acid)

Target cells of Mycobacterium tuberculosis

In lungs: Alveoli (alveolar macrophages)

Difference between pulmonary TB and Miliary TB

Pulmonary TB: TB that affects the lungs

Miliary TB: TB that spreads to multiple organs in the body through blood 

Measles Virus

Rubeola

two main surface glycoproteins on the Measles virus envelope

• Hemagglutinin (H) Protein→ binds to the host-cell receptors

• Fusion (F) Protein→ facilitates viral entry and cell-to-cell spread

classic symptoms of measles

High fever, cough, runny nose, conjunctivitis (inflammation of membrane covering white part of eye), rash from head to toe

Main transmission route of measles

Droplet trasmission

Which Poliovirus capsid protein is the major antigenic target for neutralizing antibodies?

VP1, VP2, VP3 BUT —> VP1 is the major antigenic target

path of poliovirus through the host body from entry site to central nervous system.

Poliovirus attaches to the host-cell receptor, then replicates and produces viral proteins that cause the infection.

Initial replication is in the throat or intestine, then may travel through the bloodstream to the central nervous system and damage motor neurons. 

Describe the primary target cell (tropism) of Hepatitis B Virus.

Hepatocytes (liver cells)

surface protein on the HBV envelope targeted by neutralizing antibodies and used as the immunogen in modern vaccines

HBsAg

Describe the genome structure and envelope characteristics of Influenza A Virus

Single-stranded RNA, enveloped, segmented, negative-sense

(Influenza A Virus) two primary surface glycoproteins and their roles in host cell entry and release.

HA - binds to sialic acids 

NA - allows for the release of replicated Influenza virus 

(Influenza A Virus) What specific host cell type and receptor are targeted by Hemagglutinin (HA) in the respiratory tract?

Respiratory epithelial cells

What severe clinical complication can arise from Influenza A Virus in high-risk individuals?

HA binds to Sialic acid receptors 

surface protein in Rabies virus that serves as the primary target antigen for neutralizing antibodies?

Glycoprotein G (RABV-G)

How is rabies virus typically transmitted to humans?

Through the saliva of an infected animal, usually through a bite.

Rabies pathway of progression through host tissues from the initial bite site to the central nervous system (CNS).

The virus enters the body through the wound, may multiply in nearby muscle tissue, and then enters peripheral nerves. It travels along the nerves toward the brain and spinal cord. Once it reaches the central nervous system, it becomes fatal if not treated quickly and can cause severe neurological disease. 

Plasmodium falciparum

Malaria

What type of organism is Plasmodium falciparum (Malaria)

Eukaryotic

what specific vector transmits malaria to humans

Female Anopheles mosquitoes

morphological shapes of its sporozoite and gametocyte stages of Malaria

Sporozoite is a spindle-shaped, single-celled parasite

Gametocyte is banana-shaped and responsible for transmitting disease back

Name the two human host cell types sequentially invaded by P. falciparum. Which stage is responsible for clinical disease manifestations?

Hepatocytes (liver cells) and erythrocytes (red blood cells)

The stage responsible for clinical disease is the erythrocytic stage