MID 2 - Lecture 12 Flashcards
Pathogenic protists and transmission to humans
Protozoa - adapted to every type of habitat on earth
1. arthropod vectors
2. contaminated food and water
3. Direct contact
Malaria (transmitted and cycles)
-5 species of plasmodium
By bite of infected female mosquito
-exoerythrocytic cycle (liver)
-Erythrocytic cycle (red blood cell)
-mosquito/sporogonic cycle
Mosquito stage
Gametocytes are ingested by mosquito, making an oocyst, then injects sporozoites into a human, goes through liver, then blood cells
Human stage (A and B)
A. In liver, sporozoites form schizonts, merozoites form and rupture level cells and goes into blood stream
B. invade blood cells, and replicate asexually, destroy blood cells
Malaria (clinical)
Shaking chills, fever, and sweating, anemia, cerebral malaria in children, immunocompromised = deadly
Treatment: Vaccine approved in Africia (recombinant vaccine for children), bednets and insecticide spray
Leishmaniasis
Protozoan parasite (leishmanias), sandflies when take blood meal (inject into human)
Leishmania life cycle
Sandfly blood meal (ingests macrophages infected), amastigotes into promastigote, sandfly takes blood meal (put promastigote stage in human), transforms into amastigotes again
Trypanosomiasis (general)
Human african Trypanosomiasis (african sleeping sickness), caused by T. brucei, tsetse flies, fever, headache, exteme fatigue, muscle and joint aches
T. brucei cycle
Tsetse fly blood meal, trypomastigotes into procyclic trypomastigotes into espimastigotes, tsetse fly blood meal (into human), turns back into trypomastigotes
Covid history (2 viruses before 2019)
- SARS-CoV - 2002
- Middle east respiratory syndrome coronavirus (MERS-CoV) - 2012
- SARS-CoV-2 - december 2019
Covid virus characteristics (4 structural proteins and general make up)
Coronaviridae
-enveloped, unsegmented single strand positive sense RNA genome
- 4 structural proteins - spike(glyco), envelope (glyco), membrane (glyco), nucleocapsid (proteins)
Covid entry into host (portals how it gets in - general)
nasal/oral passage, conjunctiva of eyes through nasolacrimal duct, oral cavity/esophagus
Covid (once transmitted entry) ACE2
-S proteins bind to host cells (by angiotensin) converting enzyme 2 (ACE 2)
-ACE2 proteins in tissues (kidneys, lungs, heart, arteries, gastro tract)
-s proteins embedded in viral envelope bind to ACE2 on host cells and trigger viral endocytosis or membrane fusion
Mechanisms of pathogenicity (covid)
- virus takes over replicative machinery and multiplies
- Immune system triggers inflammatory response
- Non specific immune cells release chemokine that stimulate a targeted attack on infected cells, crippling normal function
Vaccine (what kind of microbes are used)
-preparation of microbial antigens used to induce protective immunity
- Killed, living, weakened microbes or inactived bacterial toxins, purified cell material, recombinant vectors, DNA
Immunization
result obtained when vaccine stimulates immunity
Adjuvant (some examples)
ingredient in some vaccines that enhances the rate and degree of immunization
- aluminium salts, lipids, synthetic DNA
Example of viral vaccines
chickenpox, hepatitis, HPI, Influenza, measles
Examples of bacterial vaccines
Anthrax, cholera, meningococcal, TB
Comparison of vaccine types (live cell, vs acellular, vs DNA)
whole cell: live - virus, strong T response, strong B cell
Inactivated - bacteria, weak T, Strong B
Acellular - antigens from microbe, Very strong T, very strong B
Recominant and DNA - virus or vector, very strong T, very strong B
Whole cell vaccines (and some problems)
most current active against bacteria and viruses have microbes that are either killed or live (avirulent)
problems - could be weaker, immunosuppressed at risk of getting disease
Viral vector vaccines (example)
gene for pathogen antigen inserted into genome of non-pathogenic virus, released products result in immunity
AstraZeneca
Acellular or subunit vaccines and forms of it
purified molecules from microbes, avoids some risks of whole cell vaccine
-Capsular polysaccharides
-Recombinant surface antigens
-Inactivated exotoxins
Vaccine phases
- preclinical (cells then animals)
- phase 1 safety trials (small number of people)
- Phase 2 expanded trials (hundreds)
- Phase 3 efficacy trials (thousands)
- Approval (10-15 years)
Pfizer/BioNTech vaccine
mRNA encodes for spike protein, cell that uptake mRNA produce spike protein, immune system recognizes and makes defensive response, antibody production (2 doses over 3 weeks)
