Medical Important Viruses

A microscopic infectious agent that replicates only inside the living cells of other organisms. It consists of a nucleic acid genome enclosed in a protein coat called a capsid. Some viruses also have an envelope made of lipids and proteins.

A complete, infectious virus particle that contains the genetic material (DNA or RNA) and the protein coat (capsid).

The protein shell that surrounds the genetic material of a virus.

A membrane-like structure that surrounds some viruses, in addition to the capsid. It is composed of lipids and proteins.

The ability of a virus to infect a host and cause disease.

A type of genetic material found in viruses, composed of a long chain of nucleic acids that carry genetic information.

A viral infection where the virus replicates inside the host cell without killing it. The virus does not usually cause disease.

A viral infection where the virus is actively replicating and causing disease symptoms.

Classifying viruses into genera and species involves considering additional features like host range, serological reactions, amino acid sequences of viral proteins, and sequence similarity of their nucleic acids.

A virus's genome can be composed of either RNA or DNA, and each can be single-stranded (ss) or double-stranded (ds). The most common types in nature are ssRNA and dsDNA.

Single-stranded RNA genomes can be either positive-sense (messenger RNA sense), meaning they can directly be used for protein synthesis, or negative-sense (antisense), requiring a complementary strand to be created before protein synthesis can occur.

The protein shell that encloses the viral genome is called a capsid. Most viruses have either a helical (rod-shaped or coiled) or icosahedral (spherical or symmetrical) capsid structure.

Helical capsids are made of repeating units of a single type of protein, which self-assemble into a cylindrical structure. These proteins are linked together by hydrogen bonds, forming a nucleocapsid along with the viral nucleic acid.

Icosahedral capsids are more complex, consisting of numerous different proteins organized into subassemblies called capsomers. These capsomers are linked by hydrogen bonds to create a symmetrical, 20-sided structure.

The viral genome is situated within the internal space enclosed by the rigid, icosahedral structure. This structure provides protection and stability for the virus.

The capsid plays a crucial role in protecting the viral genome, facilitating attachment to host cells, and enabling entry into the host cell.

Viruses without an envelope; they have only a protein shell.

A classification system of viruses based on their genetic material and replication strategy.

A type of virus with a double-stranded DNA genome. Examples include herpes, adeno, pox, and papova viruses.

A type of virus with a single-stranded DNA genome. Examples include parvo viruses.

A type of virus with a double-stranded RNA genome. Examples include reo and rota viruses.

A type of virus having a single-stranded RNA genome with positive polarity. Examples include picorna, toga, flavi, and corona viruses.

A type of virus with a single-stranded RNA genome with negative polarity. Examples include rhabdo, orthomyxo, bunya, and filo viruses.

A genus of viruses that includes the human pathogen hepatitis E virus.

Naked viruses with two icosahedral capsid coats and 10 segments of double-stranded RNA.

A major human pathogen from the Reovirus family, causing diarrhea mainly in infants.

Enveloped viruses with an icosahedral capsid and single-stranded, linear, nonsegmented, positive-polarity RNA. They include important pathogens like hepatitis C virus, yellow fever virus, dengue virus, and West Nile virus.

A group of viruses that infect a variety of animals and cause significant human diseases, including hepatitis C.

Naked icosahedral viruses with double-stranded linear DNA, known for causing pharyngitis, upper and lower respiratory tract diseases, and other infections. There are at least 40 antigenic types.

Enveloped viruses with an icosahedral capsid and single-stranded, linear, nonsegmented, positive-polarity RNA. They are divided into two major groups: alphaviruses and rubiviruses.

Double-shelled viruses with an icosahedral capsid covered by an envelope. Their DNA is a double-stranded circle with an incomplete strand.

Enveloped viruses with an icosahedral nucleocapsid and double-stranded linear DNA. Their infections can become latent.

A group of Togaviruses that includes eastern and western encephalitis viruses.

A group of Togaviruses that includes rubella virus, which causes German measles.

The largest viruses with a bricklike shape, an envelope, and complex capsid symmetry. Known for causing skin lesions called 'pocks'.

RNA viruses categorized into two groups: Naked icosahedral viruses and enveloped icosahedral viruses.

The smallest RNA viruses with single-stranded, linear, nonsegmented, positive-polarity RNA. Divided into enteroviruses (poliovirus, coxsackievirus, echovirus, hepatitis A) and rhinoviruses.

Naked viruses with an icosahedral capsid and single-stranded, linear, nonsegmented, positive-polarity RNA.

Enveloped helical viruses with single-stranded linear RNA as their genome. They are responsible for a variety of human diseases.

Middle East Respiratory Syndrome, a serious and potentially fatal pneumonia caused by a coronavirus (MERS-CoV) that emerged in Saudi Arabia in 2012-2013. It is closely related to a bat coronavirus, and camels are believed to be the primary source of human infection. Person-to-person transmission is possible but less common.

The pandemic of coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). It was first identified in Wuhan, China in December 2019.

Fever, tiredness, and dry cough are the most common symptoms. Other less prevalent symptoms include aches and pains, nasal congestion, runny nose, sore throat, and diarrhea. Usually, these symptoms onset gradually and are mild. Many infected individuals remain symptom-free.

Around 16% of people infected with COVID-19 develop serious illness marked by difficulty breathing. Individuals with underlying medical conditions such as diabetes, high blood pressure, or heart problems are at higher risk for severe complications.

The World Health Organization (WHO) officially recognized COVID-19 as a pandemic on March 11, 2020. This declaration signaled the global spread and significant impact of the disease.