ANTI VIRAL AGENTS AND VIRAL INFECTIONS

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VIRAL INFECTIONS AND THEIR TREATMENTS

Introduction

Viruses are infectious agents without having their own cell wall or nucleus but replicate the cell content of the host as their own and convert them convenient for their life. A virus-infected cell’s physiology would be totally changed and It itself behave against its own tissue and spread rapidly to infect other cells. Hence eradicating virus is so difficult and is not as easy as bacteria

Viruses can infect all forms of life including animals, plants, microbots including bacteria. Although there are a million types of viruses are known only a few(5000 types) have been known in detail.

VIRIONS are viral particles before invading or infecting a cell of an organism packed into helical or icosahedral shaped particles with three parts as follows:-

1)The genetic material made from DNA or RNA;

2)A protein coat is known as Capsid which surrounds and protect the genetic material

3)And in some cases a lipid coat surrounding the capsid when they are outside

A cell. They may contain antigenic proteins

Some viruses contain enzymes that may initiate viral replications in the host cell.

Since viruses are not having their own metabolic systems and they use the system of the host cells such as cells of a plant, a bacterium, or an animal.

Viral replications are having various stages and accordingly antiviral agents are classified as the stage at which they are acting.

The main survival of the virus depends on how much of its strength to stay away from the defense mechanism of the host

                     

THE DNA VIRUSES

The DNA viruses are having more commonly a double-stranded or less commonly a single-stranded DNA as their genetic material. They usually use the DNA polymerase enzyme to replicate in the infected cells. But there are some DNA viruses like the one causing Hepatitis-B, which use RNA intermediate while replication. Such viruses are known as Reverse transcribing viruses as they replicate through an RNA intermediate. Other examples in this class are Smallpox, Chickenpox, and Herpes. Just spend an hour by watching the following video                                                



RNA Viruses

These viruses are having usually single-stranded RNA material and unusually have double-stranded RNA material. These viruses undergo replication only through an RNA intermediate. Examples are Ebola viruses, Hepatitis-C, Polio, and measles.

The following are the copyright-free image of RNA viruses:-                           

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  The Difference Between DNA and RNA image as follows:-

 

In DNA viruses the main genetic storage material is the Deoxyriboneuclicacid which is the storage for genetic codes that contains the pieces of information regarding various functionings and advancements of all living organisms. The DNA molecular structure is a combination of a sugar molecule known as Deoxyribose with long-stranded whether double or singly coiled nucleotide strands. These strands have narrow channels that contain enzymes difficult to penetrate. When the virus contacts and penetrate into the host cell it will infect the host membrane of the host DNA with its genetic codes and the DNA of the host cell will be replicated by RNA polymerase and behave as a duplicated viral DNA and thus the virus multiplies. But the process of mutation may not be rapid because the DNA polymerase enzyme is having refining activities. After infecting the host cell they will withstand and adjust to whatever changes take place in the host cells.

In the RNA virus, the main genetic material is Riboneuclicacid which translates the genetic codes from the DNA storage of the host cells contains all information regarding various functionings and advancements and converts them as their own into protein products. It is found in the nucleus and cytoplasm. It is usually a single-stranded molecule with shorter nucleotide chains. The sugar present is ribose. Several RNA viruses instill the RNA to the host cell and skip the DNA host for duplication and decoding. DNA here acts as a pattern for an RNA virus then transcribes it into viral proteins. Some RNA viruses embed transcriptase enzymes that transfer RNA virus to a DNA virus and combine into the host DNA. Then follows the DNA replication process.  

The mutation is mainly happening in the cytoplasm and it is rapid in RNA viral infections as unlike DNA polymerase RNA polymerase is always making error and irregular which is most favorable for the viral replications.

AIDS (HIV) VIRUS AND TREATMENTS

Nobody in the world is here without a scare about Auto Immune Deficiency Syndrome or AIDS. The pathophysiology of this disease involves the total destruction of our body's defensive system and open the gateway for invasion and infection by various microbes in our eco and environmental system in which we live in.

 The main causative organism for this disease is the Human Immunodeficiency Virus or HIV.

See the structure of the HIV

Once the virus infected our blood it destroys slowly and completely the white blood cells of the CD4+receptor containing T-Lymphocytes which is responsible for almost most of the blood's defensive system.
HIV is spreading when the blood, the sperm, or the vaginal fluids enter into another person. Unless except the above three channels there is no cause or ways for the HIV to spread.

Symptoms

Actually the HIV infection, in the beginning, will not show any significant recognizable symptoms as may the patient would misunderstand the flu. But if left unattended the infection may develop slowly into -1. Belly cramps lead to nausea or vomiting;

2.Diarrhea;3Enlarged lymph nodes in the neck armpits and groin; 4.Fever and Headache; 5.Muscle aches and Joint Pain; 6.Skin Rash;7.Sore Throat;8.Weight Loss

Pulmonary symptoms:(Pneumocystis pneumonia)

It is also known as pneumocystis carinii is very common in HIV infected nondefensive individuals caused by pneumocystis jirovecil

  It was a common immediate cause of death. In developing countries, it is still one of the first indications of AIDS in untested individuals, although it does not generally occur unless the CD4 count is less than 200 cells per µL of blood.  

Gastrointestinal

Normally esophagitis caused by fungal infections (candidiasis) and viral infections due to herpes. Mycobacterial infections are rare. 

Neurological

Toxoplasmosis is a disease caused by the parasite known as Toxoplasma gondii which usually infects the brain and causing Toxoplasma Encephalitis. This parasite can cause disease into the eyes and lungs through the neuronal spread.

Meninx the cover of the brain and spinal cord can be infected by the fungus known as Cryptococcus neoformentes to cause cryptococcal meningitis.

A virus called the JC virus will erode the entire inner lining of the nerve lumen known as axons and damage the nerve transmissions. The condition is known as Progressive multifocal leukoencephalopathy. Particularly in AIDS patients, immediate death follows a month of diagnosis

AIDS DEMENTIA COMPLEX(ADC) is a metabolic encephalopathy. This condition is caused by the HIV virus through the infected brain cells which secrete the neurotoxins and damages the nervous system.

                         

 

ANTI RETROVIRALS-AIDS TREATMENTS

Most of these agents are of the same chemistry of class 2’,3’ dideoxynucleotide analogs. All of these analogs share the common mechanism of action of inhibiting the RNA dependant DNA polymerase enzyme (reverse transcriptase) of the HIV virus.

HIV virus is a retrovirus and it is differing from other viruses by after entering the host cell as it is an RNA virus but it undergoes reverse transcription by its reverse transcriptase enzyme to become a virtual DNA virus and then it incorporates into the host cell,s DNA.

There are two types of Antiviral agents that inhibit reverse transcriptase enzyme.

1.Nucleoside analogs. 2.Non-nucleoside analogs. 

1.ZIDOVUDINE:-

 

CHEMISTRY:-Zidovudine is chemically 3’-azido-3’-deoxythymidine commonly referred to as AZT. It is a thymidine derivative active against HIV-1 and HIV-2 viruses. Also, it is active against Leukemia (human t-lymphocyte viruses or HTLV)

Actions:- It is very active in low concentration against HIV-1 in T-Lymphocyte linings and peripheral lymphocytes.Zidovudine is less active in human monocyte-macrophages but active in brain macrophages.

Nucleoside Analogs:-1.Zidovudin(AZT)

                                        2.Didanosine(ddL)

                                        3.Zalcitabine (ddC)

                                        4.Stavudine(d4T)

Other medications:- 1.Amantadine

                                 2.Rimantadine

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