Virus Classification And Description Mrs Rekha B Subject

Virus Classification And Description Mrs. Rekha. B Subject: Microbiology Class: B. Sc(N) 1 st year

RNA Virus Picornaviridae family: • These are small (20 -30 nm), nonenveloped • Icosahedral virus with single stranded RNA genome. • Mainly of enterovirus – polio • Rhinovirus – bovine • Hepatovirus – hepatitis B virus

Orthomyxoviridae family • These are medium size (80 -120 nm) spherical or elongated enveloped viruses carrying hemagglutinin and neuraminidase peplomers. • Genome consists of single stranded RNA in several pieces. • Eg Influenzavirus

Paramyxoviridae family • The Paramyxoviridae are a large family of single-strand, enveloped RNA viruses which causes a number of human and animal diseases. 150 nm (size). • Three generation are:

Paramyxovirus

Morbillivirus • Rinder pest virus

Pneumovirus

• Paramyxovirus: mumps virus • Morbillivirus: measles, rinderpest • Pneumovirus: RSV of human

Togaviridae family • The Togaviridae family is organized into two genera, Alphavirus and Rubivirus. Alphaviruses are mainly arthropod borne viruses and responsible for such diseases in humans as encephalitis and arthritis.

• The sole member of the Rubivirus genus is the Rubella virus, which is the causative agent for the common childhood disease, rubella. • Togavirus genomes contain a single, positive-sense RNA molecule.

• Togavirus particles are comprised of an envelope and a nucleocapsid. These virions are 70 nm in diameter and are spherical to pleomorphic in shape with glycoprotein projections.

Flaviviridae family • Flaviviridae viruses that cause disease in humans. • The Flavivirus genus contains several nasty critters that include yellow fever virus, dengue fever virus, and Japanese encephalitis (JE) virus.

• Genomes contain a single, positive-sense RNA molecule. • Particles are comprised of an envelope and a nucleocapsid. These virions are 40 -60 nm in diameter and are spherical to pleomorphic in shape with glycoprotein projections

Bunyaviridae family • The Bunyaviridae are a very large family of single-strand, enveloped RNA viruses (more than 300 viruses) 90 -100 nm and consists of five genera of viruses: Orthobunyavirus, Phlebovirus, Nairovirus, Hantavirus, and Tospovirus (Tospoviruses infect only plants). .

• They are found in and transmitted by arthropods (e. g. mosquitoes, ticks, sand flies) and rodents, and can occasionally infect humans. Several viruses of the Bunyaviridae virus family can produce mild to severe disease in human, in animals, and sometimes in both.

Arenaviridae family • The Arenaviridae are a family of viruses whose members are generally associated with rodent-transmitted diseases in humans. Each virus usually is associated with a particular rodent host species in which it is maintained.

• The virus particles are spherical and have an average diameter of 110 -130 nanometers. All are enveloped in a lipid (fat) membrane. Viewed in cross-section, they show grainy

Rhabdoviridae family • Rabies virus is a rod- or bullet-shaped, single-stranded, negative-sense, enveloped RNA virus. The virus genome encodes five proteins. 130 -300 nm long & 70 nm wide. • Rabies virus causes acute infection of the central nervous system.

Reoviridae family • Icosahedral, nonenveloped viruses, 60 -80 nm in size with double layered capsids. • Genome ds. RNA • Three generations : reovirus, orbivirus and rotavirus

Coronavirdae family • It is an enveloped virus aroud 100 nm, with club shaped pleomers projecting as a fringe from the surface, resembling like solar • Corona virus cause respiratory disease & neonatal diarrhea.

Retroviridae family • These are RNA tumour viruses and related agents. • Icosahedral, 100 nm in size with envelope • ss. RNA RT • Thre subfamilies are: oncovirinae, spumivirinae & lentivirinae.

Calciviridae family

• The Caliciviridae viruses are characterized as having small, positive-sense, singlestranded RNA genomes. • Virions consist of a non-enveloped capsid that is spherical or hexagonal in appearance and exhibits icosahedral symmetry. The capsid has a diameter of approximately 3539 nm.

Filoviridae family • Filoviruses belong to a virus family called Filoviridae and can cause severe hemorrhagic fever in humans and nonhuman primates. So far, only two members of this virus family have been identified: Marburgvirus and Ebolavirus.

• Viral filaments may measure up to 14, 000 nanometers in length, have a uniform diameter of 80 nanometers, and are enveloped in a lipid (fatty) membrane. Each virion contains one molecule of singlestranded, negative-sense RNA.