Mystery of hepatitis B and C viruses

 Hepatitis, also commonly known as jaundice, is a disease of the liver that causes inflammation of the liver, which causes the liver to fail to function properly. The liver performs many important functions in the human body, including digesting food, getting energy from it as needed, storing vitamins, making essential hormones, and expelling waste and toxins from the body.

Mystery of hepatitis B and C viruses

There are many possible causes of inflammation / hepatitis in the liver, but the most important cause is a variety of viruses that can also cause hepatitis. So far, five types of viruses have been identified that can cause hepatitis. These are known as hepatitis A, B, C, D and E viruses. Interestingly, they all belong to different families of viruses.

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Hepatitis A virus (HAV) is related to Picorna viridae, Hepatitis B virus (HBV) is related to Hepadua viridea, Hepatitis C virus (HCV) is related to Flaviviridea, Hepatitis D virus (HDV) is related to Delta viridae and Hepatitis. ۔ Genetically, the genomes of all four viruses, except for the hepatitis B virus, contain RNA instead of DNA. The genetic material of any living thing usually consists of DNA. So these viruses are unique in that respect.

Hepatitis A, D, and E are usually spread by contaminated water and infected food. The jaundice caused by these viruses is slightly less severe than hepatitis B and C. HBV and HCV are spread through the bloodstream through the human body, usually through the use of infected syringes and other medical devices, from the infected blood or from the infected mother to the baby. Both viruses cause acute and chronic infections.

According to the World Health Organization, there are currently about 325 million people infected with the HBV and HCV viruses in the world. About 5 million people in Pakistan are infected with hepatitis B and 10 million with hepatitis C. Both of these types of hepatitis can lead to liver cancer and both can lead to life-threatening diseases.

Hepatitis B virus

Hepatitis B virus was introduced in 1965 by Dr. Discovered by scientist Baruch Blumberg, he was awarded the Nobel Prize, the world's largest award. The virus belongs to the family Hepadna viridae. It is the smallest disease-causing virus in humans with a genome, DNA (circular-partial double stranded dua). Its genome size is only 3200bp.

This tiny genome contains four major genes of viruses called HBC, HBP, HBS and HBX. These four genes make up the seven major proteins of the virus, which play an important role in the spread of the disease and its severity, from the virus entering the human body to its replication.

The HBS virus gene, also known as HBs antigen (HBSAg), forms the outer shell or superficial protein of the virus (envelop protein). They make proteins. These proteins help the virus to enter the human cell through the hepatocyte cell membrane.

The role of this protein is crucial in diagnosing HBV virus infection. The presence of a specific amount of HBs antigen in human blood also plays an important role in diagnosing and treating the disease. The same protein is also used in the development of HBV vaccines.

HBC

The HBV and IRS gene produces the cord protein of the C virus, which is actually the inner layer of the virus's envelop. This gene also makes two types of proteins for the iris. A protein called viral nucleocapsid is the vital layer of endogenous protein that surrounds the genetic material of a virus and is called HBcAg. Another protein called HBCAg helps to spread the disease in the human body and also plays an important role in determining the severity of the disease in the body.

HBP

The HBP virus gene is the largest protein in the P virus, containing 1800 amino acids. This protein actually consists of three domains. The first domain is called the Terminal protein domain, which encapsulates the virus, that is, encloses its genome in a capsule. At the same time, this protein is involved in the important task of replicating the virus's genome. The third domain, called the Ribononucleas H domain, degrades the pregenomic RNA of the virus that forms in the cell. This protein also plays an important role in replicating the virus. ۔

Structure of hepatitis B and C

Mystery of the hepatitis B and C virus

HBX is the fourth gene of this virus called geneX which contains 154 smaller amino AG1s. These are called multifunction proteins that play an important role in the transmission of the virus from the virus to the human body. This protein converts simple jaundice in the human body into liver cancer. One of the characteristics of this gene is that it is such a unique gene that the answer has not been found in any other living thing. That is why it is called Gene X. This is a good target for HBV medicine for gene scientists.

Virus Replication

The HBV virus binds to the Heparan sulfate proteoglycan receptor attached to human liver cells and causes endocytosis or F enters usion. The nucleocapsid of the virus is then released into the cytoplasm of the human cell, after which the virus's genome enters the nucleus of the human cell. Once the virus's genome enters the nucleus, it replicates it in the form of RNA, and then the RNA leaves the nucleus and enters the endocytoplasm of the cell where the virus makes its essential protein from this RNA. ۔

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The corprotein of the virus then encapsulates the replicated DNA of the virus. The envelope proteins (SML) then combine to form the outer shell of the virus and finally the new and complete virus emerges from the cell and infects the neighboring host cells. I spread.

Genotypes of the HBV virus

The HBV virus is classified into eight genotypes (A to H) and more than twenty-five sub-genotypes based on its genetic makeup. This classification is due to the presence of seven and a half to four percent change in the structure of its genome, respectively. The HBV virus is divided into nine different serological types due to the change in the structure of its HBsAg. ۔ The role of these different genotypes and serotypes of the virus is important not only in determining the severity of the disease, but also in determining its treatment and the presence of the virus in different geographical areas.

Many antiviral drugs are used against HBV infection, with interferon and nucleoside analogues topping the list. Despite the availability of HBV vaccines and treatments, hepatitis B is a deadly virus that not only causes cancer in millions of people each year, but is also fatal.

Hepatitis C virus (HCV)

The virus belongs to the family FLAVIVIRIDAE. The virus was first discovered in 1989 by a group of scientists, including "Dr. Michael Hougton, Harvey Alters, Charles Rice", who was awarded the Nobel Prize in 2020. This virus is larger in size than HBV, which is about 55-65 nano meter in diameter. It is an Envelop virus whose genome consists of Positive Sense double stranded RNA which is about 9600 Base Pairs in length.

Mystery of the hepatitis B and C virus

Not only is it many times larger than HBV, but its structure is also different. Basically, the HCV virus genome has only one Open Reading Frame (the place where proteins start to form) which makes only one protein called polyprotein. But in the HBV virus There are four ORFs that make up its seven proteins. The single ORF in the HCV genome is broken down into three protein and seven non-structural proteins.

In addition, the HCV virus's genome contains two un-translated regions before and after its single ORF. Both of these UTRs also play an important role in the ability of the virus to replicate in human cells and to spread the disease. UTRs are the parts that do not make any proteins themselves but initiate the process of making the virus a polyprotein.

HCV gene A protein

The HCV genome consists of a total of ten genomes that make up a large polyprotein through an ORF, and then these polyproteins are cleaved into three structures, including core proteins and two envelop proteins E1 and E2. These proteins are viruses. The seven non-structural proteins, including the proteins NS5A, NS4B, NS4A, NS3, NS2, P2 and NS5B, play an important role in the formation of the IRS. They play an important role in the cancer-causing process.

Corprotein

NUCLOCAPSID forms a protective layer outside the virus genome. In addition, this protein interacts with many proteins in the human cell that play an important role in the virus's own life cycle. In addition, the role of this protein in turning disease into cancer during the disease is also important.

E1 and E2 proteins

The other two structural proteins of HCV, E1 and E2, known as envelop glycoprotein, are actually responsible for the formation of the outer layer of the virus. This protein first identifies cell receptors such as CD81, LDL-R, etc. to infect the virus cell and then connects to these receptors to help the virus enter the cell.

Protein PC suture (NS1)

HCV is a non-structural protein of the virus. This protein plays a vital role in replicating the virus and is involved in the morphogenesis of the virus.

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Protein NS2 is also called nuclear export protein. This protein also interacts with many other proteins in the human cell. This protein has auto proteolytic activity which automatically separates NS2 and NS3 from polyproteins. This protein not only replicates the virus but also plays an important role in the assembly of the newly formed virus particle. The protein NS2 prevents the automatic death of old and damaged cells in the liver by "apoptosis" and converts it into cancer. This protein also helps the virus to survive in human cells.

Structure, Components and mode of transmission of hepatitis B and C

Proteins NS3 and NS4A

These are multifunctional proteins of the HCV virus that have not only a proteolytic (protein-binding ability) but also helicase There is also activity that actually plays an important role in replicating the virus. This protein plays an important role not only in the life cycle of the virus but also in the spread of the disease in the human body. Both of these proteins can be important targets for the treatment of HCV.

Protein NS4B

This protein is critical for replicating the HCV virus. This protein provides a platform for replicating the HCV virus by altering the membrane structure of the endoplasmic reticulum of its host cell and thus plays a critical role in the virus's life cycle. ۔ This protein also inhibits the synthesis of many proteins in its host cell and stimulates the cell's immune response.

Protein NS5A & NS5B

It plays a key role in virus replication and assembly. This protein provides resistance to the virus to interferon, while the most important protein enzyme in the NS5B virus, RNA polymerase, completes the process of replicating the virus's RNA genome. It could also be an important target for scientists to develop HCV drugs.

Preparing a virus copy

VIRAL REPLICATION

The HCV virus enters human cells through its proteins E1 and E2. For this purpose, these proteins of the virus enter the host cell by binding to several receptors such as CD81, LDLR1 and then the virus's necleocapsid enters its RNA cell inside the cell. Inserts into the plasma. The virus then produces its single polyprotein with the help of% UTR which is further divided into three structural and seven non-structural proteins. The virus then replicates the virus with the help of the NS4B protein and then with the help of the protein NS3B forms RNA-dependent RNA polymerase. Thus, the virus begins to replicate the RNA.

Once the genome is fully replicated, the virus's core protein forms a nucleocapsid around the virus's genome, and then the E1 and E2 proteins form the outer shell of the virus. The virus then exits the cell and closes to nearby cells. Affects and thus the disease spreads in the body, even causing incurable diseases like cancer.

Genotypes of the HCV virus

Like hepatitis B, there are six genetic variants of HCV (genotype 1-6). These different genotypes are found in different countries of the world. For example, genotypes one, two and three are present almost all over the world. Genotype four in the Middle East, genotype five in Africa and genotype six are the source of the spread of hepatitis C in Southeast Asian countries.

Like the genotypes of HBV, the genotypes of HCV are of medical importance in many ways. The lethality of HCV can be estimated from the fact that every fifth patient with chronic HCV develops liver cancer. Scientists are trying to develop a vaccine against the virus, but so far no significant results have been found and only a few antiviral drugs and pegylated interferon are being used to treat HCV.

Importantly, viruses evolve faster than any other living thing, and the resulting genetic mutations can make these viruses even more deadly. RNA viruses evolve faster than DNA viruses, causing not only the human immune system but also drugs to lose or reduce their effectiveness against these viruses.