Before we begin, here are some terms which you should familiarise yourself with.
- Outbreak: the sudden appearance of a disease in a population
- Pandemic: an outbreak of a disease that occurs over wide geographic area i.e. on a global scale
- Epidemic: an outbreak of a disease that spreads rapidly in a community or in a restricted geographic area
Polymerase Chain Reaction
PCR can be used to identify a suspected viral infection using fluorescent primers whose base sequences are complementary to the suspected virus. Because viruses incorporate their DNA into their host cell, therefore if there is a viral infection, then the tagged primers will anneal and multiply indicating a viral infection
Enzyme Linked Immunosorbent Assay
ELISA identifies the presence of specific proteins, such as antibodies. It can use an antigen from the pathogen to bind to antibodies present in the blood, which would have been produced by the immune system. Therefore, by tagging the antigen with a dye, if it successfully binds to antibodies present in the blood, that would be indicated
Bacterial and Viral Cultures
By taking a sample of body fluids, a pathologist spreads it on an agar plate to allow for the growth of the bacteria which may be present in the sample. Further testing, including gram staining and microscopy can then determine the identity of the bacteria. If it is a suspected viral infection, then it would be cultured within cells on the agar plate
Antibiotics (Extract from Biology Unit 3 Pathogens)
Antibiotics are naturally occurring products which target cellular structures of bacteria. They are either bacteriostatic which inhibit growth or are bactericidal which kill. They mainly target protein or cell wall synthesis.
Sensitivity tests are used to determine which antibiotic is the most effective for a known bacteria species. A clear zone around the antibiotic disc indicates that the bacteria is sensitive. If there is no clear zone, then it is resistant. It is important to note that even if the area surrounding the antibiotic disc is the greatest, that is not indicative of it being the preferred or most effective in the body – as it was tested under laboratory conditions. Varying internal environments can affect the functioning of the antibiotic, for example, the children of pregnant women who have taken tetracycline can cause discolouration of their teeth.
Antiviral drugs are a type of medication that are used specifically for treating viral infections and are designed to interfere with a process in the virus’s life cycle. Therefore, antivirals can only affect actively replicated viruses, and should be administered within a certain timeframe before or after exposure. For example, interfering with DNA polymerase and reverse transcriptase, thereby blocking DNA replication or by blocking viral protease enzymes using protease inhibitors.
Serialisation (Extract from Biology Unit 3 Pathogens)
A sterile environment is something totally clean and free from pathogens. Sterilisation is the act of killing all pathogens in a designated area. It can be achieved by radiation, which consists of UV rays and gamma rays, autoclaving, which uses high temperatures to kill pathogens, and filtration
- Disinfection is the process of reducing or eliminating pathogenic agents with a disinfectant
- Antiseptics are simply disinfectants used on animal tissue e.g. betadine
Rational Drug Design
The RDD is a concept that involves the development of a drug against a disease by targeting a biomolecule that is considered central in the development of the disease. However, this biomolecule e.g. active site or receptor must be specific to the disease or does not affect any other system. For example, in the case of an enzyme being the biomolecule, the drug is designed to bind to the active site of the enzyme, preventing its activity.
Drug trials help to determine whether a drug is more effective in human treatment, is safe for human treatment or has less/any side effects with other drugs
Relenza is an antiviral drug against influenza that was designed to work as a competitive inhibitor of the enzyme neuraminidase, which is found on the lipid envelope of the virus. Neuraminidase is an enzyme that catalyses a reaction that allows virions inside the host cell to exit and infect neighbouring cells Therefore, when Relenza binds to neuraminidase, the virus can no longer cause disease as it cannot spread throughout the body