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1. "organisms at the edge of life" Tobacco Mosaic Virus by Martinus Beijerinck Genes Metabolism Division Cell Structure

2. Recall that bacteria are smaller than eukaryotes Viruses are smaller and simpler still 0.25 m Bacteriophage Animal cell Bacterium Animal cell nucleus Viruses lack energy metabolism Viruses Are very small

3. Evolution and Biology of Extremely Large DNA Viruses

4. Smallest infectious agents Most are so small, they can only be seen with an electron microscope Animal viruses Proviruses- around 20 nm in diameter Mimiviruses - up to 450 nm in length Viewing viruses Special stains and an electron microscope Negative staining outlines the shape Positive staining shows internal details

5. Viral Classification I: dsDNA viruses (e.g. Adenoviruses , Herpesviruses , Poxviruses ) II: ssDNA viruses (+ strand or "sense") DNA (e.g. Parvoviruses ) III: dsRNA viruses (e.g. Reoviruses ) IV: (+) ssRNA viruses (+ strand or sense) RNA (e.g. Picornaviruses , Togaviruses , CoVs ) V: (−) ssRNA viruses (− strand or antisense) RNA (e.g. Orthomyxoviruses , Rhabdoviruses ) VI: ssRNA -RT viruses (+ strand or sense) RNA with DNA intermediate in life-cycle (e.g. Retroviruses ) VII: dsDNA-RT viruses DNA with RNA intermediate in life-cycle (e.g. Hepadnaviruses ) Genetic material DNA viruses (double- and single-stranded) RNA viruses (double- and single-stranded)

6. HIV ( human immunodeficiency virus ) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases. It is spread by contact with certain bodily fluids of a person with HIV. If left untreated, HIV can lead to the disease AIDS ( acquired immunodeficiency syndrome ). The human body can’t get rid of HIV and no effective HIV cure exists. So, once you have HIV, you have it for life. Luckily, however, effective treatment with HIV medicine (called antiretroviral therapy or ART) is available. If taken as prescribed, HIV medicine can reduce the amount of HIV in the blood (also called the viral load) to a very low level. This is called viral suppression. If a person’s viral load is so low that a standard lab can’t detect it, this is called having an undetectable viral load. People with HIV who take HIV medicine as prescribed and get and keep an undetectable viral load can  live long and healthy lives.  

7. The virion or virus particle consists of: nucleic acid (RNA or DNA) surrounded by a protein coat – Capsid ( capsomers) envelope (if present) Originates from the host cell’s membrane Viral Structure

8. Dr. Mayilraj said, the freshwater sediments from the Ganges house several novel viruses, which were never reported earlier. These bacteriophages are active against certain clinical isolates, or viral strains and can be used against multi-drug resistant or MDR infections. Dr. Mayilraj and his team has identified 20-25 interesting  viruses, which can be used for treatment of tuberculosis (Mycobacterium), typhoid (Salmonella), pneumonia (Klebsiella and Acinetobactor ), cholera (Vibrio), dysentery (Shigella), diarrhoea ( Aeromonoas ) meningitis ( Cronobacter ), etc. “Our findings revealed variety of different bacteriophages , which have specific bactericidal characteristics,” Dr. S. Mayilraj  

9. Bacteriophage T4 , has a complex capsid consisting of an icosahedral head and a tail apparatus. Bacteriophages

10. Bacteriophages (Lytic and Lysogenic Cycle) Attachment  – the phage attaches itself to the surface of the host cell in order to inject its DNA into the cell Penetration  – the phage injects its DNA into the host cell by penetrating through the cell membrane Transcription  – the host cell's DNA is degraded, and the cell's metabolism is directed to initiate phage biosynthesis Biosynthesis  – the phage DNA replicates inside the cell, synthesizing new phage DNA and proteins Maturation  – the replicated material assembles into fully formed viral phages (each made up of a head, a tail and tail fibers) Lysis  – the newly formed phages are released from the infected cell (destroyed in the process) to seek out new host cells to infect

11. Common viral cycle (Flu virus)

12. • Immunization is defined as the procedure by which the body is prepared to fight against a specific disease Active Passive IMMUNIZATION PASSIVE IMMUNIZATION Passive immunization or immunity is produced without challenging the immune system of the body. Artificial or Natural Serum or Gamma Globulins (tetanus or measles) – from infected person (toxoid) Maternal Antibodies (Placenta or Breast Milk)

13. ACTIVE IMMUNIZATION Immunity is produced BY challenging the immune system of the body to antigens. Natural and Artificial Clinical or subclinical infections Vaccines Edward Jenner Dead Virus Attenuated (live but artificially weakened)

14. Attenuated (live but artificially weakened) Inactivated poliovirus given by injection (IPV) and a weakened poliovirus given by mouth (OPV) Inactivated (killed) polio vaccine, Jonas Salk , was announced in 1955. Another attenuated live oral polio vaccine was developed by Albert Sabin and came into commercial use in 1961 IPV: 99% OPV: 50% (one dose) 95% (three dose) July 2021, only 2 cases of wild poliovirus have been recorded globally this year to date: one each in Afghanistan and Pakistan. While OPV is safe and effective, in areas where vaccination coverage is low, the weakened vaccine virus originally contained in OPV can begin to circulate in under vaccinated communities. When this happens, if it is allowed to circulate for sufficiently long enough time, it may genetically revert to a ‘strong’ virus, able to cause paralysis, resulting in what is known as circulating vaccine-derived polioviruses ( cVDPVs ).

15. Herd immunity- It is the indirect protection from a contagious infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection. This means that even people who are not vaccinated, or in whom the vaccine doesn’t trigger immunity, are protected because people around them who are immune can act as buffers between them and an infected person. Once herd immunity has been established for a while, and the ability of the disease to spread is hindered, the disease can eventually be eliminated.

16. Aztra Zeneca Vaccine

17. Technology: mRNA Efficacy: 95% Number of doses required: 2 Dose interval: 21 days apart Administered in the Deltoid muscle with needle/syringe Vaccine require reconstitution Storage: -70°C during storage and distribution, at vaccination site could be stored at 2-8°C for 120 hours Side-effects: Side effects (such as fever, chills, tiredness, and headache) throughout the body were more common after the second dose of the vaccine. Most side effects were mild to moderate. Allergic reaction could occur within 4 hours of getting vaccinated, including symptoms such as hives, swelling, or wheezing (respiratory distress). This includes allergic reactions to polyethylene glycol (PEG) and polysorbate Pfizer Vaccine

18. Technology: Inactivated vaccine Efficacy: 50%-70% (different trial results) Number of doses required: 2 Dose interval: 14 day interval Administered in the Deltoid muscle with needle/syringe Fully liquid vaccine Storage: 2-8°C Side-effects: Most adverse reactions were mild, with the most common symptom being injection-site pain Sinovac Vaccine