MICR 200B infections and diseases

Influenza A virus (IAV),- enveloped -'ve sense RNA virus

• Replicates in epithelial cells of the upper respiratory tract

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SARS-CoV-2,- coronavirus = enveloped, non segmented, +'ve sense RNA virus.

• First 2/3rds of genome encode NSP 1-16 = proteins for RTC complex

• second 1/3 encodes remaining proteins required

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human immuno-deficiency virus (HIV),- enveloped, single stranded +'ve sense RNA virus.

• Jumped to humans from animals (SIV)

• transmission is sexual or by blood exposure

• infection targets CD4+ cells, especially those in the gut

lymphoid tissue.

• Treated by daily anitviral therapy (ART)

Herpes viruses,- Large double stranded DNA virus

• posses α, β, γ1 and γ2 genes ( each correspond to when the genes are expressed

• all undergo cellular latency in host = lifelong persistance

Herpes simplex virus (HSV),- a herpes virus

• infection can be oral or genital

• Lifelong infection results from virus inserting its genome into

T cells

Varicella Zoster virus,- A herpes virus

• causes chicken pox (Varicella) or Shingles (Zoster)

• establishes latency in the neurons of the cranial nerve

Rheumatic fever/ heart disease,- caused by repeated infection by S. Pyogenes (GAS)

• GAS evades immune response by mimicking self antigens

• leads to the creation of antibodies that target cardiac tissue, concentrating damage on the heart valves

Multiple sclerosis (MS),- Leaked to infection by Epstein Barr virus

• auto-reactive B and T cells as well as microglia (CNS macrophages) inflict damage and inflammation

• T cells activate B cells to produce auto-reactive antibodies

• Leads to neuron demylenation

Severe Lupus Erythematosus (SLE),- systemic (Whole body)

• Unknown cause

• Immune system responds to multiple self-proteins

• Dendritic cells are activated causing a cascade tha results in

auto antibody production

Celiac disease,- Infammatory autoimmune response to gluten

• expression of MHC-2 molecules for gluten

• results in loss of gut villi

Allergies,aberrant immune response to an external, non-harmful antigen

• loss of tolerance, not autoimmunity

Streptoccocus pyogenes,- opportunistic infections

• usually cause strep throat (pharyngitus)

• Virulence from superantigens, toxins and DNAses

• treated with penicillin

0 can cause rheumatic fever if repeated infection

Neisseria menigitidus,- opportunistic pathogen in nasopharynx

• causes meningococcal disease in blood

-> fever, neck stiffness then coma and death

• transmitted via aerosol droplets attach w/ IV- Pilus

• treated w/ gen 3 cephalosporin

Haemophillus influenzae,- opportunistic pathogen in ear and sinus

• If co infect w/ respiratory infection causes sever pneumonia

• Types A-F, capsulated are more pathogenic

• vaccine exits for Hb, otherwise trated with penicillin or cefotaxime or ceftriaxone if resistant

Bordetella pertusis,- causes whooping cough

• tracheal toxin prevents cilia from beating while pertusis toxin targets the immune system

• vaccine exists w/ attachment factors of the toxins

Characteristic of staphylococcus,

S. aureus,- coagulase positive

• resident in up tp 50% of humans

• can be an opportunistic pathogen

• some strains resistant to antibiotics

S. epidermidis,- coagulase negative

• produces a capsule

• forms biofilms on medical implants

• some innate antibiotic resistance

• efficient skin colonizer

• toxins that kill leukocytes or can bind antibodies in an inccorect orientation to evade immune system

S. saprophyticus,- coagulase negative

• colonizes groin (inguinal region)

• pathogenesis linked to adhesions

• resistant to novobiocin

Diseases of S. aureus,- Forms abscess, that require draining or antibiotics

• If systemic, can infect bones (osteomyelitis)

• Induce toxinoses, toxic shock syndrome or food poisoning

EPEC,enterropathogenic E coli

• LEE operon for binding

• T3SS to inject bacterial effectors

EHEC,enterrohemorroagic E.coli

• Produce shiga toxin, which inactivates protein synthesis

Shigella,causes bacillary dysentary (shigellosis)

• vomiting and bloody diarrhea

can also encode shiga toxin

Salmonella enterica,some serovars are pathogenic

• serovar typhi causes typhoid fever

can cause salmonellosis (food poisining)

Listeria monocytogenes,disease characterised by flulike symptoms

can cause meningitis

invades host cells via actin rearangement

meningitis,swelling of membranes surrounding the brain and spinal chord

Vibri cholerae,causes cholera

cholera toxin cause the efflux of ions, resulting in fluid loss from the cell and diarrhea that will dehydrate the host, resulting in death

Yersinia pestis,highly resistant to phagocytes

T3SS

tretable with streptomycin

can cause bubonic (lymph), pneumonic (lungs) and septicaematic (Blood)plague

Berrelia bugdorferi,transmitted via ticks and nymphs

causes Lyme disease

• bulls eye rash then autoimmune response similar to

rheumatic fever