Antivirals

Viruses: Small biological agents that can infect every organism and reproduce only inside the living cells of such organisms. Viruses are essentially cores of DNA or RNA ( deoxyribosenucleic acid or ribonucleic acid, respectively) surrounded by regularly packed proteins that are called capsomeres. Viruses that infect cells usually cause them to produce more of the virus instead of performing its cellular functions, thus causing the cell to die or take massive damage.

Differences between viruses and Bacteria: While bacteria can replicate in non-living surfaces, viruses can only do so in living cells. Viruses mutate the organism's cells such that it no longer works normally and instead produces more of the invading virus. Viruses are packages of information that affect the host, and thus not truly living, while bacteria are actual cellular organisms

How antiviral drugs work: Common diseases that arise from viruses,(like influenza or mumps), are usually fought of by the body without the aid of any drugs thus must of the medicine taken for them is just to alleviate the symptoms (like runny noses.) Most symptoms produced by viruses appear at a time in which antiviral drugs have little effect due to the fact there are too many viruses already. Some antiviral have been recently developed to combat only the viral infections they are made for. Antivirals like acyclovir, changes the cell to make it impossible for it the virus to multiply. Acyclovir is usually used to combat cold sores the come from the herpes virus. Aclovir is structured like DNA and thus tricks the virus into attempting to replicate with the Acyclovir and not the cell. Acyclovir does not completely eliminate the virus and thus is may resurface again. Ganciclovir is a drug similar to acyclovir that is employed in the case of resistant viruses that are not affected by acyclovir. Different types of antiviral drugs work by destroying the viruses’ ability to reproduce and leave the cell. An example of these is amantadine which is a drug used when afflicted with the influenza virus and works by neutralizing neurminidase which is the enzyme that the influenza virus uses to stick to the host cell wall. Acyclovir Glanciclovir Amantadine http://www.bmb.leeds.ac.uk/mbiology/ug/ugteach/icu8/antibiotics/antivirals.html

HIV/AIDS: The human immunodeficiency virus (HIV) which can lead to acquired immunological deficiency syndrome (AIDS) is a virus that regularly mutates making it hard for antiviral drugs to be created. Such a syndrome leaves men prone to secondary infections and tumors. HIV is a retro virus which means that it contains RNA instead of DNA. The virus invades T helper white blood cells, which should normally allow the immune system to work, and suppresses it. Once invaded the reverse transcriptase enzyme makes the viral DNA from the viral RNA which serves as template. Normal cells make RNA from a DNA template using RNA polymerase as the enzyme. Many drugs have been created to fight this virus. AZT (ziovudine) has a similar structure to acyclovir and works by combining the reverse transcriptase enzyme and suppresses it. Since this enzyme is exclusive to retro viruses AZT does not harm normal cells. Despite the fact that no known cure or vaccine has been invented for HIV, a variety of drugs can delay AIDS from being acquired and delay death for patients that already have AIDS. This is the reason why the best way to combat AIDS is still to use preventive methods like condoms to prevent the exchange of bodily fluids.

zivudine http://www.bmb.leeds.ac.uk/mbiology/ug//icu8/antibiotics/antivirals.html

HL Stereochemistry: The ability of a drug to work depends on its interaction with specific molecules in the body or in the virus, which means that the stereochemistry of the drugs is very important. Drug molecules that have two carbons double bonded with each other or a ring whose rotation is restricted then the drug's structure could have geometrical isomerism. Geometric isomers might have completely different effects when used on the human body. For example, diamminedichloroplatinium (II), which has the formula Pt(NH3)2Cl2 has a cis and trans isomer and also happens to be square planar. The cis isomer is used to treat ovarian and testicular cancer while the trans isomer does not work well with cancer. Both isomers diffuse through the cancer cell membrane (as they have no overall charge) and exchange chloride ions for a molecule of H2O to form Pt(NH3)2Cl(H2O)+. This new ion has the ability to enter the nucleus of the cell yet only the cis isomer can combine the two guanine molecules present in the DNA by once again exchanging a chloride ion to create Pt(NH3)2(DNA)2+. Such a molecule changes the cancers DNA as to not be able to copy itself correctly and therefore die. Antiviral molecules that posses chiral carbon atoms exist in different enantiomeric forms. Some examples are analgesic ibuprofen, amphetamine, and thalidomide.

http://www.chemcases.com/cisplat/cisplat06.htm

Practice questions: What are the essential similarities and differences between bacteria and viruses? Explain the difference between bacteria and viruses in terms of structure and their ability to reproduce/replicate, How is virus different from bacteria?

Explain how common antiviral drugs work How does a virus replicate itself? How is this different from bacteria? How do antiviral drugs function to disrupt virus? How does the drug acyclovir interrupt virus replication? What is a retrovirus? AZT or zidovudine has been developed as an antiviral drug for the treatment of people who are HIV positive. Explain how this antiviral drug works to attract the HIV virus? How does AZT function to attack the AIDS virus?