Acquired Immunodeficiency Syndrome, Essay Example

Introduction

The AIDS (Acquired Immunodeficiency Syndrome) epidemic is one of the greatest medical battles that have baffled the civilized world. Worldwide, more than 33 million people are infected with the virus HIV (Human Immunodeficiency Virus). As of 2008, twenty million people have died of complication related to the virus (Fauci, 2008). The outbreak of the HIV/AIDS is both a social and medical problem that has disrupted the lives of millions by causing fear and uncertainty of the future. This disease has many effects on the victims and their families. People suffering from HIV/AIDS are unable maintain employment. They have mounting medical debts that can lead them to mental despair. When the victims finally succumb to the disease and even greater challenge must be faced if the victim had small children. Often these children are orphaned due to the social stigma that is placed upon them by society. This stigma causes them to be isolated from other members of society; often even their family abandons them. There are many ways that HIV/AIDS can be transmitted from one person to the next: sexual intercourse, blood transfusions, from mother to child, or sharing needles can pass the disease on to the next person. Most AIDS cases are linked to ignorance about the disease. So, many people are unaware of how the disease is transmitted and how to protect themselves from it. The greatest percent of people living with the disease are those from poverty, limited education, and no health care coverage. According to the Center for Disease and Control Prevention there is an estimated 1,148,200 people aged 13 years and older living with the disease in the United States alone. This number includes 207, 600 people who are infected and do not know it. In June of 1981, the United States reported it first known case of AIDS. Initially, it was believed that this disease was something that would only affect the gay community. Through further research, it is now known that this epidemic does not specialize in any certain characteristics; any person is subject to it. Because this disease is so devastating, the development of an effective vaccine is of utmost importance.

How Are Vaccines Tested

Any vaccine has to successfully go through three phases of clinical trials before it is deemed safe for human use. The first phase can last up to eighteen months and the last phase can take up to three or four years to complete. During the first phase, volunteers help researchers test the safety and tweak dosing. The second phase may have hundreds of volunteers that continue to test safety and check for negative side effects.  The final phase may involve thousands of volunteers. In most cases, each trial has an equal number of people who are HIV negative and positive to adequately judge how the drug affects the body. Scientists want to see how the drugs may delay the progression of the disease and how different life styles may affect the disease.  The international HIV Vaccine Initiative reported that in March 2013, there were three vaccines being tested in phase II, one phase I/II, and thirty-four in Phase I. The first vaccine to undergo phase III trials was called AIDSVAX. These trials began in 1998-1999. Two separate studies were conducted on this vaccine. There were about 5400 participants in the study, mostly gay American men and the remaining were IV drug users in Thailand. At the end of the study, no beneficial vaccine was discovered (Fauci, 2008).

Challenges

A great deal of progress has been made in the development of HIV vaccines in the past several years, but many challenges still remain.  To date, there are about forty vaccines being testes to combat the AIDS virus. The way the envelope covering the HIV cell is designed limits the accessibility of neutralizing antibodies to penetrate the envelope.Four major HIV vaccine efficacy trials -Vaxgen, Inc. conducted AIDSVAX 003 and AIDSVAX 004; NIH-supported HIV Vaccines Trial Network conducted HVTN 502 or STEP and HVTN 503 have failed to effectively penetrate the envelope surrounding the AIDS cell(Blower& Schwartz, 2003). When the vaccines were able to penetrate the envelope, they failed to neutralize the HIV in the blood of the infected person. HIV is a member of the lentivirus family. Lentiviruses are known for their ability to lay dormant for long periods of time. For example, “Conventional approaches for the detection and identification of infectious disease are likely to fail in cases where the organism is hidden in inaccessible tissues, has already been eliminated, or is a novel microorganism for which no test exists. In such circumstances, transcriptional immune signatures can be a valuable tool” (O’Gara,). HIV particles are made up of two identical strands of RNA surrounded by an envelope that contains virally encoded glyproteins.

DNA Vaccines

DNA vaccines are small portions of DNA that contain genes from HIV which are grown in bacteria. Using purified plasmid DNA as a vaccination includes injecting the plasmid into the subjects in hopes of eliciting an immune response from the subject. These DNA vaccines are intended to boost the immune system of the person with HIV in efforts to fight off the diseased HIV/AIDS cells. Seddon says,” Our immune system has an impressive arsenal at its disposal designed to keep the various bacteria, viruses and other pathogens in our environment at bay. Because there are fundamental differences between our chemistry and that of bacteria and viruses, we have successfully evolved immune mechanisms that recognize and exploit these differences to identify and eliminate such foreign invaders” (Seddon, 2012). This type of vaccine is one of the safest methods with limited side effects. Following the DNA immunization, viral antigens mimic antigen during a natural infection.  Scientists are using several strategies to modulate response to DNA vaccines.

Attenuated & Inactivated Vaccines

The most powerful way to create a vaccine is by weakening or “attenuating” the pathogen. These types of viruses are harmless to humans, but fool the body’s immune system to boost its response to threat. To create an attenuated vaccine, one must delete genes that protect the virus, but are not needed for the reproduction of the virus. However, “Live attenuated HIV vaccines are currently considered unsafe, after research in monkeys indicated that a live-attenuated vaccine, made by deleting the nef gene, protected monkeys against SIV, but caused AIDS, albeit more slowly than the normal virus” ( Burton & Desrosiers, 2004) ). Nonetheless, animal research in live attenuated vaccines continues.  Another technique is creating vaccines for “killed” viruses. This is the same technique that was used to create the first successful polio vaccine. Nonetheless, it is a risky procedure because participants could be infected with HIV if the inactivation process fails. Scientists question the long term effects of killing off bacteria. For example, “

For non-bacterial infections, mutants of the human immunodeficiency virus, the causative agent of AIDS, are rapidly becoming resistant to antiviral drugs, and amongst the parasitic protozoa resistance to the front-line anti-malarial drugs is now widespread. The human race would not die out if all antimicrobial agents became ineffective but undoubtedly mortality would increase and life would be much more uncomfortable and less predictable than at present” (Buxton, 2001).

So, although the human race is battling a right now epidemic, thought must be given to future complications future human beings may face. If this tampering goes badly, humans of the future may be unable to fight off common infections or become resistant to common antibiotics.

Therapeutic Approach Showing Promise

In 2013, scientist reported that an experimental therapeutic vaccine temporarily lowered the level of HIV in the blood of infected persons. The Vacc-4x usedmodified antigen-presenting dendritic cells that lowered the viral blood count in victims for several months. Although the effect did not continue, it gave scientist hope that the concept would work. A vaccine of this type could eventually lead to a functional cure by controlling HIV replication without the use of antiretroviral drugs. Normal vaccines are designed to prevent the HIV infection, but to date none have worked. In contrast, therapeutic vaccines are intended to treat people infected with the virus by boosting the immune system. “In around 80% of patients receiving treatment, the virus was suppressed and CD4⁺ levels were maintained two years after therapy began” (Fauci, 2008). Studies have shown that therapeutic strategies in conjunction with antiviral drugs have been shown to slow the progression of AIDS. Yet, there are still problems with viral drug resistance and toxicity “because there are fundamental differences between our chemistry and that of bacteria and viruses, we have successfully evolved immune mechanisms that recognize and exploit these differences to identify and eliminate such foreign invaders” (Seddon, 2012).

Conclusion

Great strides have been made in the fight to find a cure for the HIV/AIDS epidemic. Over forty vaccines are currently being tested in hopes of curing or stopping the progression of the disease. Therapeutic methods seem to show the most promise. HIV/AIDS is not a discriminatory disease. Anyone from any background can be affected. Consequently, efforts must be made to educate the population about this disease, how it is transmitted, and how one can protect himself from it.

References

Blower, S., E. J. Schwartz, et al. (2003). Forecasting the future of HIV epidemics: the Impact of antiretroviral therapies & imperfect vaccines. AIDS Rev 5(2): 113-25.

Burton, D. R., R. C. Desrosiers, et al. (2004). HIV vaccine design and the neutralizing antibody problem.Nat Immunol 5(3): 233-6

Buxton, R. (2001). Superbugs-the problem of antimicrobial resistance. Mill Hill Essays.

Fauci, A., (2008).  25 Years of HIV. Nature 453(1): 289-90.

O’Garra, A. (2012). Immune signatures in disease and visions for their future use. Mill Hill Essays.

Seddon, B. (2012). A key for every lock in the universe-the blindlocksmith? Mill Hill Essays