Last year in South Korea, a male 26-year-old AIDS patient was held in custody for sexual abuse of multiple victims. He worked as a taxi driver for about a year and a half between 2007 and 2009, and was found guilty for sexually abusing six female customers. He was actually pronounced that he was a positive AIDS patient in 2003. According to his statements, the motive of his actions was out of revenge that he had the infection. The person whom he had gotten HIV from is unidentifiable (Chosun.com). This incident caused chaos in South Korean society and the need for educating public about HIV infections and AIDS is essential in order to improve their knowledge and to implant proper prevention methods. HIV is a human immune-deficiency virus, which causes disease in human. This virus contains enzymes, such as reverse transcriptase and integrase that make the virus unique from the other viruses. HIV infects the cells of the immune system and cause death of CD4 T cells, which is the core initiator of the immune system. The symptoms of long term HIV infection eventually lead to clinically termed syndrome called, acquire immunodeficiency syndrome (AIDS). HIV infections and AIDS have been one of the leading causes of death worldwide due to lack of prevention and treatment. Because this virus has such unique characteristics that are different from other present viruses, further studies are required to enhance the treatments and possible vaccine production.
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HIV is one of the retroviruses that infect human. It is a single-stranded RNA virus which belongs to Baltimore class 6 due to the presence of DNA intermediate, retroviridae family, orthoretrovirinae subfamily, and lentivirus genera. HIV is divided into HIV-1 strain, which causes the common HIV infection and HIV-2 strain, which rarely causes the infection with less lethality than HIV-1 strain. HIV-1 is subdivided into three different groups including group N, group M, and group O, which are further divided into clades A through J. The different groups and clades of HIV-1 strains vary geographically, and they all respond differently to treatments. The structure of HIV is complex. It is enveloped virus with tulip shaped viral proteins embedded in the membrane, conical shaped capsid with two identical pieces of its genome inside. There are important proteins of HIV which allow their unique replication processes. The viral proteins on their envelop membrane are GP41, which is inserted in the membrane that allows fusion to occur and GP120, which is on the surface of the envelop that allows attachment to proceed with cellular receptors. More proteins are found inside the envelope, such as matrix protein, which gives the envelop structure and capsid protein, which makes up the conical shaped capsid. In addition to the structural proteins that are important in attachment and entry of the virus, the most important proteins of HIV are found inside the capsid attached to the genome that includes reverse transcriptase for DNA intermediate synthesis and integrase for viral genome integration into human chromosome and protease to make infectious proteins (Kohl et el., 1988). The genome of HIV has nine open reading frames which encode for fifteen proteins and are incredibly well organized by their functions. The genome can be divided into three regions, GAG gene regions that contain genes which encode for all the enzymatic proteins, POL gene regions contain genes that encode all the polymerase enzymes, and ENV gene regions that encode all of the structural proteins (Wensing et al., 2009). The unique structure of HIV explains why they cause such a deadly disease in human and why it is so hard to prevent and treat the virus (Parilla, Jessica 2010).
As briefly mentioned above, HIV has unique proteins that are essential in their replication cycle upon infection. Since HIV is a single-stranded RNA virus, it follows the regular RNA replication cycle of attachment, entry, uncoating, transcription, translation, genome replication, assembly, and egress. The only exceptions are the two additional steps that are unique to HIV, reverse transcription and integration. Attachment occurs between viral proteins GP120, GP41 and cellular receptors CD4, CCR5 or CXCR4. CCR5 and CXCR4 are co-receptors and only one of them is required along with CD4 for attachment to occur. As you can see, HIV attaches to the cellular receptors that are found mostly in the immune system, such as CD4 T cells, macrophages, natural killer cells, dendritic cells, CD8 T cells, or neuronal cells. This explains why this virus is named human immunodeficiency virus and how it interferes with the immune system. After attachment, GP41 protein found in the envelop membrane causes fusion event to occur between viral envelop and cellular membrane, thereby causing uncoating event to occur in the cytoplasm. One of the disparate characteristics of HIV replication occurs at this point with the released genome in the cytoplasm. The reverse transcriptase that are attached to the viral genome reverse transcribe the viral RNA genome into DNA intermediate and makes double stranded DNA. The newly synthesized double stranded DNA gets inside the nucleus with the help of shuttling proteins and the most lethal process occurs inside the nucleus. Viral enzyme called "integrase" integrates viral DNA into human chromosome. Once the viral genome is integrated into the human chromosome, there is no turning back. The viral genome gets replicated every time cellular genome replicates and finishes the life cycle using the host replication strategy. After all the necessary proteins and new viruses are made, the assembly occurs underneath the cellular plasma membrane where the viral envelop proteins are already inserted. The newly synthesized viral genome recognizes the site on the plasma membrane where viral proteins are embedded in, and it is taken up by budding acquiring the envelope with it. Newly pinched off virion must go through a maturation step where the acquired proteins are cleaved by viral protease to make mature infectious virus (AIDSinfo and Parilla, Jessica 2010).
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HIV pathogenesis occurs in multiple steps which eventually lead to AIDS. Primary HIV infection causes acute syndrome which causes both cell mediated and humoral immune response to occur. During this acute infection period, virus is replicating in enormous amounts per day and spread to the lymphatic system causing mild disease with fever, malaise, and swollen lymph nodes. This acute infection period is also called the window period because the immune system is slowly responding to the infection by activating CD4 T cells, but antibodies for HIV has not been made yet and the infected person is highly contagious. As the infection progresses, it goes into clinical latency phase where viruses are kept within the lymphatic system and the viremia levels are fairly low. During clinical latency phase, antibodies for HIV are secreted in high amounts as CD4 T cell accounts drop significantly. CD4 T cells continuously die off due to other infections rather than from HIV. Human are susceptible to various bacteria, fungus, and virus infections every day. Every time HIV positive person gets infected with any kinds of infections, already infected CD4 T cells get activated and the virus become lysogenic provirus going into the lytic phase making new viruses. Therefore, available CD4 T cells in the body decrease dramatically causing loss of immune function and this eventually leads to decrease in antibody secretion as well. At this point, there is no immune response to control the virus and the HIV infected person now has AIDS. Symptoms of AIDS are indirect symptoms of the virus. The virus itself cannot cause any symptoms, but the loss of immune function leads to infections from all the pathogens out there, such as kaposiââ‚¬â„¢s sarcoma, pneumonia, tuberculosis, herpes zoster, thrush, cadidiasis, cytomegalovirus, bacterial infections, fungal infections, encephalitis, lymphoma, and many more (Castro et al., 1993). Multiple infections in AIDS patient can lead to death. Because this is such a fatal disease, prevention is important (Castro et al., 1993 and Parilla, Jessica., 2010)
The treatments of HIV are limited because of their unique life cycle. Once the viral genome has been integrated into human chromosome, the only available treatment is the cocktails of multiple types of drugs to supportively treat symptoms. The current cocktails of HIV drugs are called the highly-active anti-retrovial therapy (HAART), where each drug targets different cycles in viral replication. There are anti-HIV drugs available for almost all the steps in the viral life cycle, such as drugs that block reverse transcription, integration, maturation, fusion event, or cleave event. However, anti-HIV drugs have down sides, such as high toxicity to the patients, not able to attack viruses that are latent in inactivated CD4 T cells, or induced mutations. Vaccines are currently under studies. The problem with producing HIV vaccines is that regular vaccine strategies are not applicable with HIV because HIV infects immune system cells. The present vaccine strategies can only be able to control the spread of the virus, not the initial infection. In addition, HIV being a RNA virus can evolve quickly making it harder in surveillance of HIV strains. Even if the possible strains can be detected, the clinical trials are limited because HIV being very selective to the host tropism, it cannot be tested on either human or animal. Therefore, HIV infected person is supportively treated with multiples of anti-retroviral drugs or in clinical settings if required due to multiple infections. Because HIV treatment is limited, prevention is extremely important. HIV transmits by sexual contact, via blood, or as vertically from mother to baby. As a result, safe sex practices and careful usage of needles are the key elements in prevention of HIV. HIV positive pregnant woman can take anti-HIV drugs during pregnancy and recommended to deliver by C-section (Parilla, Jessica. 2010).
According to HIV infosource.org, the numbers of worldwide HIV incidents are leveling off after a huge peak in late 1990s. Even the countries that had the highest rates of HIV infections are showing declining trend of HIV infections (HIV infosource.org). However, HIV infections and AIDS are still the leading cause of death in certain countries. HIV is not selective in race and ethnicity although it is more likely to infect group of people who have multiple sex partners, low socioeconomic status, drug addiction, or men whom engaged in sexually active relationship with another homosexual men (apositivelife.com). According to the ViiV healthcare in appositivelife.com, the high risk factors can be divided by several different categories, such as gender, race and ethnicity, socioeconomic status, age and place of residence. Men are more likely to engage in multiple sexual relationships than women due to some cultural beliefs and characteristics in certain countries, also men are more likely to use drugs than women statistically thereby increasing the chance to be infected with HIV (ViiV healthcare). Although race and ethnicity do not contribute to the selectivity of HIV, African-American and Latinos are more susceptible to HIV infection due to the high percentage of African-American and Latino population lacking education, employment, and power (ViiV healthcare). As far as age is concerned, young people are at higher risk then older people because of lack of knowledge on HIV and other sexually transmitted diseases. Overall, a person living in poverty with no available education on these viruses is at higher risk than others who are able to get quick medical attention upon exposure and have certain degree of knowledge on these viruses. The epidemiology of HIV infection is alarming worldwide especially in South Africa and East Asia. Center for disease control estimated 56,300 new HIV cases and 1,106,400 persons living with HIV infection at the end of 2006. Those numbers correlate to the United States only. South Korea has total population of 48,700,000 and of those, 13,000 are living with HIV infection and new HIV cases are increasing (Epidemiology fact sheet). According to WHO, reported cases of AIDS in South Korea from 2002 to 2006 shows that females with symptoms of AIDS outnumber men and the trend is still increasing (Epidemiology factor sheet). The reason in increasing female cases of AIDS is due to cultural beliefs and increasing rates of sexual abuse in South Korea. As explained in the introduction, HIV and AIDS patients are not under strong surveillance system in South Korea making every citizen at risk. There should be strong law enforcement for disease controls in order to prevent healthy people from getting HIV.
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Since late 1990s, scientists have been working hard to identify this deadly virus that caused unexplainable symptoms in patients. After all of their hard works, the virus has been identified and named as the human immunodeficiency virus. Nonetheless, the virus has come up with their own unique ways of preventing treatments and immunity by carrying enzymes that are not present in their hosts. This is a tragedy for human population because the current technology and knowledge are insufficient to fight off the virus. Until the suitable vaccines and viable treatments that can be made, governments should continuously emphasize on the consequences of HIV to general public so that people are aware of this refractory problem.