Mechanisms of Viral Transmission

Mechanisms of Viral Transmission Most of the new viral diseases that enter the human population are enzootic viruses that have changed their hosts. These enzootic viruses tend to have a severe effect in humans. A viral disease emerges in a population through a series of steps the initial infection, the spillover, and lastly the host to host transfer. These steps are further aided or prevented by the virulence factors present in the virus versus the host or human whichever the case susceptibility. It is important to determine the source of these viruses and whether it was via an enzootic or epizootic virus. The barriers that the virus faces when trying to infect a new host are just as important as the role that the environment plays in the viruss transmissibility. There are many factors to consider when looking at viruses how viruses change hosts. New viruses can emerge in a population through contact with an alternative host. Until recently the probability of a virus changing hosts was limited by the restricted contact between the initial host and the alternative host. An increase in contact can be accomplished by introducing the host animal to domestication or any other arena that would serve to increase the likelihood of human contact. Primates that have been infected with simian immunodeficiency virus in Africa were separated from areas of high human populations which in turn significantly limited the chances of the virus changing hosts and infecting humans. The chances of viral contact can also be increased by changes in social and sexual behavior, increased travel, hygiene practices and the increased density of the population that work in favor of the virus and increase the chances of infection in an alternative human host. The significance of initial host to alternative host contact can be examined through the instance in Africa where primates infected with simian immunodeficiency virus in Africa were removed from areas of high human populations and in turn significantly reduced the number of the host changes from primate to humans. The removal of the infected animal from direct human contact does not prevent transmission though intermediate hosts. In Malaysia fruit bats are the reservoirs for the virus nipah and with the large number fruit orchards near pig farms the incidence of contact between the virus and the pig is greatly increased. When it comes to a viruss ability to infect a new host there are new barriers that the virus must learn to penetrate. An important part of a viruss ability to infect new hosts is its ability to infect that hosts cells. In humans the viruss can have trouble entering the host via due to factors that fight off viral infections or something as simple as the surface of human skin can pose as a barrier for entry into an alternative host. When galactosyl producing virions which are not normally found in humans are detected in the body the galactosyl brings about an antibody response that inactivates the virus and prevents its spread. A mechanism of action such as this requires the viruss need to rapidly adapt to bypass the barriers that are set up to prevent viral infection. Even if the relative distance in relation between the initial host and the alternative host of a virus is close the intensity and rate of the contact between the two species is still a factor. When a virus infects a new host that is distantly or closely related to the previous host it does not mean that the host cannot also transfer the virus to more distantly related organism. Integration of a virus into a new host cell is also dependent on the receptor binding that occurs between the virus and host cell. The changes that the virus has to undergo in order to infect the new host cells must coincide with the receptors that are found already on the host cells. A process involving the transfer of the FPV virus to infect canine involved a gain of two mutations that then allowed for it to bind to the canine transferrin receptors. These mutations allowed for the FPV virus to increase its host range successfully gain the ability to infect canines with a new form of the FPV virus CPV. Blockades for the spread of the viral infection once it has infected the new host cells can exist in the form of proteins that prevent the spread of the virus to neighboring cells. The capsid proteins of viruses are stopped at the cytoplasm of the new host cell by TRIM5ÃŽ ± a protein that binds to the capsid of the virus preventing its entry into the host cell. Generalist and specialist viruses are two categories for viruses that can possibly predict and help determine the ranges of hosts that a particular virus can infect; and whether or not a virus is a candidate for host switching. Generalist viruses are expected to have an increased incidence of alternative host shifting while specialist viruses are the opposite and are unable to bypass the barriers in the host cells receptors and other defenses that would require the virus to mutant in order to effectively infect the cell. Most of the specialist cells have trouble making it past the initial infection of the alternative host. Viruses that have a wide range of hosts have a built in advantage already in that they do not have to alter in order to successfully make a change in the types of organism that they can infect. The rate of variation in a virus directly determines the adaptability of a virus into a new host. Viruses that have a high evolving rate are more likely to cross species and cause infection in a new host due to its ability to quickly adapt to the host cell. RNA viruses do not have proofreading mechanisms as well as replication that is error prone and are in that sense much more variable than DNA viruses. DNA viruses are less variable than RNA viruses but some exception exist in that certain single stranded DNA the rate of variation may be similar to that of RNA viruses. A reduction in virus fitness occurs when the virus undergoes mutations that are necessary in order to infect a new host. If the virus is using a intermediate host even more adaptations are required and the virus is further reduced in fitness. The addition of the intermediate hosts help to explain why the influenza A virus infects each of its hosts differently through different mechanisms. In humans for example the infection is found in the lower respiratory tract than in other hosts where it is located in the upper respiratory tract. Reassortments and recombinants aid in a virus adaptability to a new host cell by making a number of genetic changes in a shorter amount of time. The CoV virus of the bat in recombination with another virus was able to make a new virus SARS that can infect humans and other hosts. The intermediate virus is a form of the virus that infects the intermediate host. This virus is the least stable form of the virus. The lower fitted virus loses some of the capability to infect previous parental host types efficiently in addition to the newer crossover hosts they are trying to infect. This phenomenon could account for the low percentage of viral crossover between species. The article did a good job of following the trend and mechanism with which a virus switches hosts. More investigation should be done in the areas of the initial infection of the virus and how it crosses over. More studies should also be done on the likelihood of a virus from another animal making the host switch to infect humans and how that spread can be predicted and prevented. Further studies should be done on how the viruses that make the jump to a species that is not close in the evolutionary chain to who they normally infect to humans. A broader knowledge of how the virus adapts itself to survive in an organism that is so different from its original host also deserves further investigation. If the topics of interest listed are further studied and developed then the article would have a more focused and concise viewpoint instead of the disorganized and sometimes abandoned thread of thoughts that exist at some points within the article.

Biased Elections in the House of Representatives :: Politics Political Essays

Biased Elections in the House of Representatives Elections for the United States Congress have become increasingly biased in favor of the incumbents. The problem is especially prevalent in the House of Representatives, which is designed to be the legislature closest to the people, and therefore most reflective of the people’s views. However, unlike elections for governors or presidents, the congressional races are generally not competitive races. While an incumbent president does have some advantages over a challenger, they are not guaranteed the win. In fact, two of the last four presidents lost their bid for re-election, Jimmy Carter in 1980 and George Bush in 1992. However, in the last four House elections, on average, 92.7% of the incumbents seeking re-election won (Vital Statistics on Congress). There are many reasons for this trend in the House, and just as many possible solutions, but most are likely to fail. However, if the House is to remain truly representative of the people and of the changing times, clearl y something must be done. It is at first surprising that incumbents don’t always win in the Senate also. But this is not the case. The incumbent success rate since World War II is only 75% in the Senate, a much more reasonable number. Because the Senate carries more prestige than the House, it is not surprising that Senate races would be more hotly contested. Most people who run for the Senate already hold a public office of some kind, or for some other reason have good name recognition. These two things explain the competition in the Senate, both candidates are generally competent representatives, and people are already familiar with them. However, most candidates running for a House seat do not have a prestigious political background. Because of this, a candidate must either have some other form of name recognition or have a lot of money to get it. Unfortunately, most people don’t have either of these, and this is why the House incumbents win 93% of the time. One possible solution to this problem, the one Americans are currently enacting, is to do nothing. While the incumbent success rate for re-election is extraordinarily high, there is still turnover in the House due to retirement for various reasons and losses in campaigns. For example, in the 1994 elections, 48 people retired and 38 incumbents were defeated in the election.

Comparison Between The American Revolutionary War And The 11 States Secession From The Union

The American Revolutionary War which occurred between 1775 and 1783 a conflict that involved the Thirteen United British colonies in North America and the Kingdom of Great Britain. The thirteen colonies had been established between 1607 and 1733 as a result of the British colonization in North America. The thirteen states desire to overthrow the British rule and to acquire independence motivated the revolutionaries to fight for the control of the Thirteen British Colonies from the British rule.As a result of the war, the thirteen colonies were able to overthrow the British Empire governance and gain independence to become the United States of America. Self –governing independent states were formed by the colonies, which then became united in order to defend their independence or self-governance against the British rule. At the end of the war, the thirteen colonies were able to break away from the British Empire rule, and they became independent under the 1776 Declaration of In dependence.The secession of the eleven southern states from the US Federal government(Union) resulted to the American Civil War which occurred between 1861 and 1865 . The secession resulted to the formation of the Confederate States of America(Confederacy),which was supported by all the border slave and free states. Due to the difference in opinion between the anti-slavery northern states and the slave-owning southern states, the conflict was triggered. The secession was motivated by the southern states fear of losing control over the federal government to the northern states.The southern states also intended to continue with slavery, which the northern states did not support. Both the American Revolutionary War and the secession have certain similarities and differences. Discussion Similarities between the American Revolutionary War and the Eleven Southern States Secession One major similarity between the two historical events is that, one opposing side in the conflicts was motivat ed by the need to be independent. In the American Revolutionary War, the thirteen colonies under the revolutionaries fought against the British rule in order to be independent.Before the conflict, the thirteen colonies were part of the British America which was under the British rule under a set of mandates, dominions, and protectorates. During the secession of the eleven southern states, the states fought for their independence from the Union or the then US Federation government. While the desire to be independent was triggered by different reasons for the two events, the major reason of the two conflicts was to seek sovereignity.The Southern states wanted to be independent so as to practice slavery and continue owning slaves without the influence of the anti-slavery northern states, while the thirteen states wanted their independence from the British unpopular and illegitimate rule. Another similarity between the two is that, the parties that sought to be independent were successf ul. In the American Revolutionary war, the thirteen states were able to get independence and sovereignty to become the United States of America. The secession of the eleven states on the other hand led to the independence of the states from the Union to form the Confederate of States.However, the independence of the southern states was short lived and it ended in 1865. In the two events, there was the use of military forces . The American Revolutionary War involved the British, and the revolutionary and the allies forces. The secession ended with the American Civil War, where the Confederacy and Union forces fought. The Differences The two events were different based on the military forces that were involved in the conflicts. The American Revolutionary War had the other outside military forces assisting the two conflicting parties in the war.However, the secession of southern states and the resulting American Civil War was a conflict between two American forces (the Union and the Co nfederacy forces), where the Union forces were made up of the northern states, while the confederacy forces were made up of the southern states. In addition, the two events were motivated by different reasons to be independent. While the American Revolutionary War resulted from the thirteen states desire to be independent so as to prevent the British rule imposing of taxes and laws that were unpopular , the eleven Southern States desire to be independent was motivated by the states support of slavery.Did the Constitution require a Perpetual Union? The Perpetual Union played an important role in the formation of the US Constitution. After defeating the British rule, the governing constitution of the thirteen independent states was the Articles of Confederation and Perpetual Union. This made it possible for the formation of the â€Å"United States of America† and the confederation government. The states were therefore able to retain their sovereignity. The establishment of a fe deral system of governance made it less important for some content of the Articles of Confederation and Perpetual Union to be put in the constitution.However,the perpetual union constitution paved way for a more powerful and balanced government. The need to have a more powerful government and balance legislative decisions of small and large states motivated the replacement of the Articles of Perpetual Union with the US Constitution . Abraham Lincoln made an inaugural address in March 4, 1861 in relation to the constitution and the Union. According to his speech, Lincoln recognized that the Union was older than the constitution.The Union had been formed much earlier than the constitution under the Articles of Association in 1774, and the 1776 Declaration of Independence continued the union. After getting their sovereignity, the Thirteen States had accepted to be in the Perpetual Union in 1778 under the Articles of Confederation. Lincoln through his inaugural address acknowledged the importance of the Perpetual Union by stating that the 1787 move to establish and ordain a US Constitution was to improve the earlier formed union into a perfect union.ConclusionThe American Revolutionary War and the secession of the eleven southern states are two historical events that have contributed greatly to the American history . The activities that took place during the two events have continued to mould the American society up to date. These two events were very beneficial to the American people because they managed to obtain their independence from the British rule, and the social injustices (slavery) fought against. Though many people lost their lives during the conflicts, the American people continue to enjoy the benefits that resulted from the conflicts up to date.Works Cited Chambers, John. The Oxford Companion to American Military History. Oxford University Press, 1999 Heidler, David. Encyclopedia of the American Civil War: A Political, Social, and Military History (20 02), 1591–98 Higginbotham, Don. The War of American Independence: Military Attitudes, Policies, and Practice, 1763–1789. Northeastern University Press, 1983 Kenneth, Stampp. â€Å"The Concept of a Perpetual Union,† The Journal of American History, Vol. 65, No. 1 (Jun. , 1978), pp. 5-33 Weintraub, Stanley. Iron Tears; America's Battle for Freedom, Britain's Quagmire: 1775- 1783. New York: Free Press, 2005

The Catholic Church and Charity - 1333 Words

The Catholic Church has been around since 100 AD. While it has been a place of worship for over 1.1 billion people all over the world, the Catholic Church is not just a source of faith for those same people. The Catholic Church is one of the world’s largest sources of charity. The Catholic Church serves billions of people all over the world every year with a large range of services. The Catholic religion is dominated by the theological philosophy that one must be a good person, but also give back during the course of their lifetime. With charity being one of the core values of the Catholic religion, it is no question that the Catholic Church is quite probably the largest charity in the world. The Catholic Church provides for the poor by giving them a place to eat and stay, they allocate funds for many types of organizations involving helping the downtrodden and people who cannot help themselves, and most importantly, the Catholic Church has a large network of people who go on missions to different countries to help spread the religion of Catholicism, but also help the people there build homes, water treatment facilities, and help them with an assortment of other health related tasks such as AIDs prevention and malaria prevention. The Catholic Church’s main priority in regards to their charitable contributions to the world is the fight against poverty. Catholics have been trying to help the poor for quite some time now. 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