Pathology: Virology

Final term SY 2023-2024

Viruses

Viruses

These are the smallest infectious agents (ranging from about 20 to 300 nm in diameter) and contain only one kind of nucleic acid (RNA or DNA) as their genome.

Virion

It is the term for the entire infectious unit.

Replicative cycle

In this cycle, numerous copies of viral nucleic acid and coat proteins are produced.

Capsid

This coat protein encases and stabilizes the viral nucleic acid against the extracellular environment and facilitates the attachment and penetration by the virus upon contact with new susceptible cells.

Capsid

The protein shell, or coat, that encloses the nucleic acid genome.

Capsomeres

Morphologic units seen in the electron microscope on the surface of icosahedral virus particles.

Capsomeres

It represent clusters of polypeptides, but the morphologic units do not necessarily correspond to the chemically defined structural units.

Defective virus

A virus particle that is functionally deficient in some aspect of replication.

Envelope

A lipid-containing membrane that surrounds some virus particles.

Envelope

It is acquired during viral maturation by a budding process through a cellular membrane.

Peplomers

Virus-encoded glycoproteins are projections exposed on the surface of the envelope.

Nucleocapsid

The protein–nucleic acid complex representing the packaged form of the viral genome.

Structural units

The basic protein building blocks of the coat. They are usually a collection of more than one non-identical protein subunit.

Protomer

Another term of structural unit.

Subunit

A single folded viral polypeptide chain.

Virion

The complete virus particle.

Virion

This structure serves to transfer the viral nucleic acid from one cell to another.

Poxviruses

These viruses are large and complex that they might represent evolutionary products of some cellular ancestor.

Virion morphology; Virus genome properties; Genome organization and replication; Virus protein properties; Antigenic properties; Physicochemical properties of the virion; Biologic properties

7 basis of virus classification

Virion morphology

This property includes size, shape, type of symmetry, presence or absence of peplomers, and presence or absence of membranes.

Virus genome properties

This property includes type of nucleic acid (DNA or RNA), size of the genome, strandedness (single or double), whether linear or circular, sense (positive, negative, ambisense), segments (number, size), and nucleotide sequence.

Genome organization and replication

This basis of virus classification includes gene order, number and position of open reading frames, strategy of replication, and cellular sites.

Virus protein properties

This property includes number, size, amino acid sequence, modifications, and functional activities of structural and nonstructural proteins.

Antigenic properties

This property includes reactions to various antisera.

Biologic properties

This property includes natural host range, mode of transmission, vector relationships, pathogenicity, tissue tropisms, and pathology.

viridae

Suffix used in naming virus family names.

Human parvovirus B19

This virus replicates in immature erythroid cells and causes several adverse consequences, including aplastic crisis, fifth disease, and fetal death.

Anelloviridae

This family of virus include the torque teno viruses, and are globally distributed in the human population and many animal species.

Polyomaviridae

This family of virus has the ability to produce tumors in infected hosts.

JC virus

This virus under the family of Polyomaviridae is the causative agent of progressive multifocal leukoencephalopathy.

BK virus

This virus under the family of Polyomaviridae is associated with nephropathy in transplant recipients

Merkel cell virus

This virus under the family of Polyomaviridae is associated with the majority of Merkel cell skin carcinomas.

SV40

This primate virus under the family of Polyomaviridae can also infect humans.

Human Papillomaviruses (HPV)

These viruses are the causative agents of genital cancers in humans.

Papillomaviruses

These viruses are very host and tissue specific and cannot be grown in cultured cells in vitro.

Adenoviruses

These viruses can cause acute respiratory diseases, conjunctivitis, and gastroenteritis.

Hepadnaviruses

These viruses can cause acute and chronic hepatitis; persistent infections are associated with a high risk of developing liver cancer.

Herpesviruses

These viruses can cause spreading nature of skin lesions.

Herpes simplex types 1 and 2

This virus is the causative agent of oral and genital lesions.

Varicella-zoster virus

This virus is the causative agent of chickenpox and shingles.

Epstein-Barr virus

This virus is the causative agent of infectious mononucleosis and association with human neoplasms.

Human herpesviruses 6 and 7

This virus is the causative agent of T cell lymphotropic.

Human herpesviruses 8

This virus is the causative agent of Kaposi sarcoma.

Poxviruses

This virus is the causative agent of smallpox, vaccinia, and molluscum contagiosum in humans.

Poxviruses

This virus is the causative agent of cowpox and monkeypox in animals.

Enteroviruses

These are viruses causing common colds to humans. Members of this group are polioviruses, coxsackieviruses, echoviruses, and rhinoviruses.

Picornaviridae

This family of virus can infect animals such as foot-and-mouth disease of cattle and encephalomyocarditis of rodents.

Astroviruses

These agents may be associated with gastroenteritis in humans and animals.

Caliciviruses

They are similar to picornaviruses but slightly larger. Important human pathogens are the noroviruses (eg, Norwalk virus), the cause of epidemic acute gastroenteritis.