Immuno - Microbial Infection Flashcards
What are viruses?
Not cells in their own right - obligate parasites
What do viruses contain as their genetic material?
DNA or RNA
How do viruses replicate?
Using cells nuclear replication machinery
What type of specificity do viruses exhibit?
Show some host cell specificity however they infect almost all other forms of life.
How do viruses divide from one another?
Budding from host cells, sometimes allowing the virus to have an outer membrane.
Or cytolysis where a host cell ruptures, therefore releasing virus into the environment.
What are the routes of viral infection?
Faecal oral
Blood borne
Air borne
Insect vectors
What is an example of a virus, its genetic material and its ability to replicate and divide?
HIV is an enveloped virus that contains RNA and there reverse transcriptase. HIV allows the host cell to survive after budding.
What are bacteria?
Prokaryotes
What do bacteria lack in terms of cell structure?
No organelles or internal membranes
What bacteria have internal membranes?
Photosynthetic bacteria (not pathogenic)
Are prokaryotes haploid or diploid?
Haploid
What does the haploid number of chromosomes in a bacteria mean in terms of effect?
Mutated genes in bacteria will always have an effect.
What makes up the cell wall of bacteria?
Peptidogylcan
How do bacteria divide?
Binary fission - very rapidly cells can reach rapid numbers due to exponential division
What is the role of the pilli?
Important for cell adhesion
What is the role of capsule?
Prevent cells desiccation and hinder phagocytosis
What is the role of the flagella?
Aid in motility of the cell
How is the shigella bacteria transmitted and were does it affect?
Faecal oral route - affects the GI tract.
Why does the shigella bacteria have no flagella?
Cells has developed a mechanism so that it can nucleate host cell actin filaments at the tail of the bacteria. This then allows the bacteria to be propelled around the cytoplasm and thus infect other cells
How do pathogens evolve so quickly?
Viruses have no way of correcting mistakes made in DNA replication unlike the polymerases of human cells. This makes viruses much more prone to expressing mutations. Also, bacteria divide at a much faster rate via binary fission and they are haploid, meaning that the rate of expressed mutation occurs a lot more quickly.
What are fungi?
Single celled eukaryotes
What are the 3 groups of fungi?
Cutaneous
Mucosal
Systemic
How do we classify fungi?
Based on where they infect/ cause mycoses which is the term for ideas caused by fungi.
What can fungi occur as?
Yeasts, filaments or both.
What is the difference between yeasts and filaments?
Yeasts can bud or divide, filaments (hyphae) have cross walls or septa
What is an example of a fungi?
Candida Albicans
What are protozoa?
Single celled eukaryotes
What does protozoa include?
Intestinal, blood and tissue parasites
How do protozoa replicate?
Either via binary fission or through the formation of trophozoites
What is the life cycle of a protozoa?
Complex life cycle involving 2 or more host cells
What is the method of infection for protozoa?
Usually through an insect or invertebrate vector.
What is Genus plasmodium?
Causes malaria
How is malaria transferred?
Mosquito vector
How does malaria replicate?
Forms mosquito belt and generates trophozoites within the cell which then utilise tissue and blood parasites.
What is Leishmania species?
Causes leishmaniasis
How is leishmaniasis transferred?
Sandfly vector
How is leishmaniasis replicated?
Trophozoites inside cell and utilises blood or tissue parasites
What are Helminths?
Multicellular metazoa with eukaryotes
What are metazoa?
Organism that contains differentiated cells and tissues
Are helminths microscopic?
No - they are often visible to the naked eye.
What is the life cycle of helminths?
Life cycle occurs outside of the host cell therefore they do not require a vector intermediate.
What are the 3 main types of helminth?
Roundworms (Ascaris)
Flatworms (Schistosomes)
Tapeworms
How do we often treat helminth infection?
Chemotherapy however this is not very efficient
What are one of the three human disease causing species of flukes?
Schistosomes
What do schistosomes require?
A small intermediate host, such as a freshwater snail
When do people get infected with schistosomes?
When they enter contaminated water.
How does a schistosome infect someone?
Cercaria from freshwater snails burrow into the skin of the affected person and migrate to the liver. In the hepatic portal vein, pairs of adult worms release eggs which go back towards the faeces via the gut. However, on their way back, the eggs travel through tissues to cause inflammation as these eggs have spines on them.
How do we treat schistosomes?
Antimicrobials are available however programmes to remove freshwater snails have also been effective.
