BIOLOGY SAC

Virus structure

Contains genetic material either DNA or RNA, and a protein capsid with spike proteins (if envoloped)

Virus structure Monkeypox

Large, ovoid, envoloped, double-standed, linear DNA virus.

Replication of Monkeypox

Replicates within the cytoplasm rather than the stereotypical nucleus. Almost independant to the cells machinery

Monkeypox has its own RNA polymerase and is using ribosomes to synthesise its proteins

Virus clade

Closely related viruses with a recent common ancestor

Virus Strain

a genetically distinct linage separated from another strain by one or more mutations

why is identification of virus clade or strain useful?

- Track the spread

- Speed of spread

- Treatment

Antiviral drugs

Medication used for treating viral infections. Most antiviral drugs target specific viruses. Broad-spectrum antivirals are also available

How human populations have become increasingly exposed to new pathogens

Smallpox vaccines have been discontinued, so those under 40 most likely will not have been vaccinated and could be exposed again.

Mutations have occurred to a different virus such as influenza and COVID 19 making it harder to stay protected against all the strains themselves

Zoonosis

An infectious disease that is transmissible from animals to humans.

Incubation period

The incubation period of an infectious disease is the time interval between the exposure to a disease-causing infectious agent and the onset of symptoms.

Infectious disease

First line of defence

Solid or fluid obstacles that block pathogen entry

- intact skin

- mucus secretions

humoral immune response

1 - A pathogen, antigen presenting cell and T helper cell all presenting the antigen of the pathogen, select a B cell with complimentary receptors - CLONAL SELECTION

2 - Signalling molecules called cytokines are secreted from the TH cells and cause CLONAL EXPANSION of B cells

- Cytokines also stimulate the differentiation between B plas cells and B mem cells

3 - Plasma cells secrete antibodies that target the antigen on the pathogen and enhance its removal from organism

4 - B memory cells retain the ability to recognise and respond rapidly to the antigen (pathogen) upon a later encounter

cell-mediated immunity

1 - A pathogen, antigen presenting cells (macrophages and dendritic cells) and T helper cells all presenting the antigen of a pathogen, SELECT a naïve T cell with complimentary receptors. - CLONAL SELECTION

2 - Signalling molecules called cytokines are secreted from TH cells and cause CLONAL EXPANSION

- Cytokines also stimulate the differentiation between Cyto T cells and T mem cells

3 - TC cells interact via receptors with foreign cell antigens and release perforins and other enzymes (granzymes) to kill the foreign cell

Structure of antibodies

- contain two heavy chains and two light chains

- have constant region and variable region

- each antipody can bind to two antigens of the same type

Vaccine

Preparation containing antigenic material that is either injected into the muscle, under the skin or taken orally to induce active immunity in an individual

Attenuated vaccine

Altered pathogens that have reduced virulence eg measles

Inactivated

Pathogens that have been destroyed to no longer cause disease eg influenza

Toxoid

Toxin produced by pathogen has been altered eg tetanus

Virus-like particle

Protein capsid with antigens on the surface similar to original pathogen eg Hep B

Primary immune response

SLOWER

Takes time for antigen to be presented and find matching B or T cell. Clonal selection and expansion and differentiation occurs to make memory cells. Antibody concentration decreases over time.

secondary immune response

FASTER

Memory cells activated and produce Abs quicker. Can be presented artificially through vaccines or naturally through infection

Natural immunity

Occurs without human intervention

Artificial immunity

Occurs with human intervention

Passive immunity

When a person is given antibodies Short lasting

Active immunity

When a person develops their own antibodies. Long lasting

Emerging

A virus that is either newly appeared, notably increasing in incidence or has potential to do so

re emerging

Diseases that reappear after they have been on a significant decline

Herd immunity

Where non immune individuals when a high % of the population is immune to the same disease. Ofeten due to high vac rates

Quarantine

A restriction on the movement of people, animals and goods which is intended to prevent the spread of disease

Justice

Respecting the rights of others and fairness

Share vaccines

Beneficence

Maximising the good outcome

Gov encourages people to take pub health measures to stop the spread

How do antibodies fight infection?

attach to antigens (foreign substances) — such as bacteria, fungi, viruses and toxins — and remove them from your body

How do cytotoxic T cells fight off infection?

T cell responsible for eliminating substances the immune system identifies as harmful