Anti Immunology : Evasion Of The Host Immune System By Bacterial And Viral Pathogens

When we hear the word virus, we usually think of something that makes us sick. A virus is an ultramicroscopic infectious organism that, having no independent metabolic activity, can replicate only within a cell of another host organism. A virus consists of a core of nucleic acid, either RNA or DNA, surrounded by a coating of antigenic protein and sometimes a lipid layer surrounds it as well. The viral genome provides the genetic code for replication, and the host cell provides the necessary energy and raw materials. To fight viruses, we use vaccines. While some may infect a broad range, other viruses can only infect certain kinds of cells. Vaccines are made of inactive, dead or weakened virus cells or protein antigens that can no longer infect

g. By using antigen concentration to deduce the path of infection, the body’s immune system may try to fight off the antigen invader. Therefore, a limitation may be that the results are a little skewed as some of the antigens may have been killed by the body’s defense. Also, each person is different, so the body’s response to these foreign objects would have varied.

Viruses are microscopic particles that invade and take over both eukaryotic and prokaryotic cells. They consist of two structures, which are the nucleic acid and capsid. The nucleic acid contains all genetic material in the form of DNA or RNA, and is enclosed in the capsid, which is the protein coating that helps the virus attach to and penetrate the host cell. In some cases, certain viruses have a membrane surrounding the capsid, called an envelope. This structure allows viruses to become more stealthy and protected. There are two cycles in which a virus can go into: lytic and lysogenic. The lytic cycle consists of the virus attaching to a cell, injecting its DNA, and creating more viruses, which proceed to destroy the host. On the other hand, the lysogenic cycle includes the virus attaching to the cell, injecting its DNA, which combines with the cell’s DNA in order for it to become provirus. Then, the provirus DNA may eventually switch to the lytic cycle and destroy the host.

Imagine the bacteria as robbers trying to invade a house, the body in this analogy. The immune system is the police officers in charge of the house, and the meninges are the alarms around the point of the house that the robbers want to come in through. The robbers trick the police officers into helping them rob the house. The robbers used the police officers, originally intended to do good.

The body’s protection against viruses, bacteria and other types of invasions is our immune system (Tortora, 2014).

Based on research and observation, we now know that infectious diseases are caused by microorganisms (pathogens) and that the immune system provides defense against infectious diseases.

Many books that can be read will captivate you, can give you another world to live in, can sweep you off of your feet and never set you back down again. Rarely can a book alter your view so entirely about the world you live in, just by giving you more information about what exactly your world is made up of. The book Good Germs, Bad Germs did this for me. Each chapter strategically broke down the history of microbes and bacteria and how they have been perceived (or not perceived) throughout history. Each expanding step lists the theories that were building blocks for the future of the study of microbes. From Nurse Nightingale, Colonel George Waring, Antoni van Leeuwenhoek and Bonnie Bassler there were medical advances that helped the field of medicine greatly. Even groups who did not believe in the germs made large steps to clean up the population. Each person mentioned in the book had some sort of contribution to the start of fighting against bacteria and viruses, with Nurse Nightingale disinfecting the work area, Waring started cleaning up the streets and created the way to keep sewage separate from the drinking water and Leeuwenhoek who identified bacteria in the first place.

Throughout my college career, I have taken courses in: epidemiology, organic chemistry, microbiology, infectious diseases, biostatistics, and public health. All my courses have helped me establish a broad and expansive understanding of public health and the multiple fields that it consists of/overlaps with. In the infectious disease course, which I completed this past semester, there was a focus on the microbiology lab techniques used in identifying disease, including: equipment, mediums, and chemical reagents used to do so. The course also focused on the biology of infectious diseases including immune responses and treatment/prevention and how that relates to identifying them in a lab setting as well as the public health implications. My epidemiology

In immunocompetent hosts, viral titers in the lung increase 1-2 days post-infection, reach a maximum at 3-5 days, start to decline at day 7, and are cleared between day 9 and day 14 (19). Early (day 2) p.i., the viral titers in the lungs of WT and NK-depleted mice were identical (not shown). As viral replication reached more significant levels at day 4 p.i., there was a trend toward increased viral load in NK-depleted animals, but these did not reach statistical significance (Fig. 5D). At day 6 p.i., a time point at which peak numbers of IFN-γ+ NK cells occur in the lung, a significant increase in VACV titer was observed in anti-NK1.1-treated mice, and this high titer continued in some animals through to day 9. Despite this, both NK-depleted and untreated NK-sufficient WT controls cleared VACV between day 9 and day 14, directly correlating with the kinetics of weight loss recovery. To further assess the anti-viral activities of NK cells, we investigated the dissemination of VACV from the lung to peripheral tissues. At day 4 p.i., there was a 10-fold increase in VACV titers in ovaries from NK-depleted mice (not shown). Again, VACV titers continued to increase over the next two to five days but were minimally detectable by day 14 (not shown). Notably, NK-depletion did not affect all organs, because an increase in infectious virus was not found in the liver, spleen, heart, and kidneys (not shown). These data suggest that NK cells provide a temporary barrier limiting VACV replication and dissemination during the acute phase of

Throughout history there have been many people intrigued by the idea of microbes. Many of those who have pursued this flitting notion may have been disappointed. Others have been wildly successful with the methods they made up or borrowed. Sometimes the discoveries they make are purely based on chance or what you can call a lucky accident. The novel Microbe Hunters by Paul De Kruif documents thirteen scientists in total with twelve intricate chapters. In particular three scientists by the names of Leeuwenhoek, Metchnikoff, and Paul Ehrlich have contributed greatly to the scientific community. They have presented great accomplishments which have benefited the study of immunology. This discipline is crucial to succor humanity in their fight against pathogens and disease.

Immunology basically involves understanding the immune system and how it responds to various disease conditions. the immune system consists of a number of components. Traditionally, it is divided into humoral and cellular immune responses. It can also be distinguished into innate and adaptive immunity. The innate immunity can discriminate between normal tissues , self and newly encountered non-self-proteins while the adaptive immunity is the more complex system aimed at the eradication of intracellular pathogens. To do this, antigen derived from such pathogens that are often new to the host organism, need to be recognised by receptor-bearing specialised immune cells which respond to a complex system of stimulatory and costimulatory signals. Better understanding of the human immune system has led to the identification of a number of tumor-associated antigens in the 1980s and the development of various immunotherapeutic approaches. In recent years, identification of the specific antigenic MHC class I epitopes, advancements in genetic engineering, gene delivery, and cell-based therapeutic approaches allowed development of the novel immunotherapeutics.

The bacteria have an ability to fight the normal bodily process of eliminating germs. Recently, the mechanism used by the bacteria to avoid detection has been identified. The typhoid bacteria use a protein to kill macrophages, which are our first defense against infection. Without these macrophages, infection goes unnoticed into the body. (sciencedaily.com) Killing these macrophages is the key to survival for the typhoid bacteria. Researchers identified in mouse cells a protein kinase called PKR that causes the death of this macrophage, or large white blood cells that act as the body's first defense against

This kind of immune response to a persisting pathogen, or direct lysis by the persisting pathogen, causes damage to self-tissue and releases antigen from damaged tissue are taken up by APCs, and this initiates a self-specific immune response. ‘A domino effect can occur, where the non-specific activation of one arm of the immune system leads to the activation of other arms. infection may lead autoimmunity through the processing and presentation of ‘cryptic antigens’. In contrast to dominant antigenic determinants, subdominant cryptic antigens are normally invisible to the immune system. The inflammatory environment that arises after infection can induce increased protease production and differential processing of released self-epitopes by APCs.Bystander activation’ describes an indirect or non-specific activation of autoimmune cells caused by the inflammatory environment present during

Action: NK cells kill tumor cells, microbes and virus infected cells in vitro without prior exposure. NK cells are regulated by activating and inhibitory receptors.

If a pathogen breaches barriers: innate immune response result into an immediate effect of non- specific response. All Innate immune systems derived from plants and animals, when a pathogen evades the innate response, a third layer of protection is possessed by vertebrates in which activation of adaptive immune system takes place. The immune system response adopts itself within an infection and pathogen recognition is improved. As a result of the improved response, its then retains itself when the pathogen is eliminated in form of an immunological memory and allows the adaptive immune system to mount faster and stronger when pathogen is encountered each time.