End of Year Exam Essay plan PDF

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- Intro: Introduce what antigenic shift and drift is, explain their general mechanisms o Antigenic drift comes from the accumulation of mutations in the genes of the original virus strain to produce a new, closely related strain o Antigenic shift comes from the combination of genes from multiple vir...

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Intro: Introduce what antigenic shift and drift is, explain their general mechanisms o Antigenic drift comes from the accumulation of mutations in the genes of the original virus strain to produce a new, closely related strain o Antigenic shift comes from the combination of genes from multiple viruses to form a novel virus with a reassorted genome Body: o Influenza A for antigenic drift, talk about its antigenic drift mechanism  Talk about its epidemiology and then how its linked to antigenic drift  Influ A has 2 types of surface proteins: Haemagglutinin (for host cell entry) and Neuraminidase (for daughter virion release)  Mutations in the haemagglutinin and neuraminidase genes causes the proteins to change shape slightly into any of the 18 types of H and 11 types of N, producing different H and N combinations  The mutations in the genes will accumulate making the proteins change shape over time. This causes the host to have a gradually weaker immune response as the virus mutates because the host will have antibodies only for the original strain of the virus.  Eventually, a mutated form of the virus allows influenza A to evade the immune response and then infect hosts that do not have the antibodies for the mutated strain.  This increases the probability of the certain strains to spread slowly whilst humans do not have the antibodies for the mutated strains.  Since the spread of the virus through antigenic drift is slow, it tends to cause small epidemics instead of pandemics  How it affects population  The antigenic drift process is the reason for why there have been multiple influenza outbreaks by different strains (e.g 1977 russian flu by H1N1 and Hong kong flu H3N2) and why it is difficult to eradicate.  As the virus mutates, the surface proteins can change into any of the 18 types of H and 11 types of N, meaning that the antigenic drift prevents populations from being able to reach herd immunity.  This causes us to produce new influenza vaccines each year that target different subtypes of H and N, since the vaccine from a previous year would not produce an immune response as effective against a strain that has arose more recently. o Influenza A for antigenic shift, talk about its antigenic shift mechanism  Talk about its epidemiology and how its linked to antigenic shift  Influ A can also undergo antigenic shift. An example of this is the Pandemic H1N1/09 virus, which caused the 2009 swine flu pandemic.  The RNA strand in Influenza A is separated into 8 segments  In a situation where multiple influenza A strains infect a host at the same time, the 8 segments from the genomes of each strain will be replicated and mixed to produce an entirely new virus with a reassorted genome. In the case of the 2009 swine flu outbreak, this occurred when pigs were infected with a combination of bird, human and swine viruses.  The reassorted genome from antigenic shift causes an abrupt change in the shapes of H and N proteins, in contrast to the gradual change caused by antigenic drift.

Since the novel virus has never been introduced before, no host has antibodies that can potentially protect them from it.  How it affects population  Because of the lack of protection that the immune system can provide towards a novel virus, viruses that undergo antigenic shift can spread through a population more rapidly.  As a result, the pandemic H1N1/09 virus that arose from antigenic shift caused a large scale pandemic rather than epidemics, affecting potentially 700 million humans worldwide. Conclusion: quick, conclude and compare by stating similarities and differences 

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- Intro: introduce what a biofilm is and what they do -

Body: o Biofilm can prevent antibacterial from penetrating (slow down penetration), prevents them from being killed  Certain antibacterials can still penetrate biofilms, such as R-pyocins o Resistant bacteria can protect whole population  Not always tho if antibacterial is broad spectrum o Nutrient gradient makes some bacteria grow more slowly; slow growing are more resistant because of dormancy (persister cells) and many antibiotics attack active processes  Antibiotics like polymyxin B, R-type pyocins and Complement membrane attack complexes (MAC) can target the cells physically by creating pores to make cellular contents flow out

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Gram-negative rod: o Gram staining then under microscope Yellow irregular colonies with dry crusty appearance: o Bacterial lawn – grow colonies Obligate aerobe: o Tube with nutrient agar Natural lysine auxotroph: o Screening check lecture 12 Catalase positive: o Add hydrogen peroxide Oxidase positive: o Oxidase test check video 10 Sensitive to ampicillin and rifampcin; resistant to gentamicin and tetracycline: o Antibiotic discs Genus Pseudomonas (16S rRNA sequence analysis): o PCR to amplify short DNA sequences o Compare to other 16S sequences to identify species Serology for antigen analysis Oxidation/Fermentation test? Bacteriophage typing

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