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[[Ficheiro:Baltimore Classification.png|right|thumb|300px| <center>Classificação de Baltimore para vírus.</center>]]
 
A '''Classificação de Baltimore''' é um sistema de [[classificação dos vírus|classificação viral]] desenvolvida pelo biólogo americano [[David Baltimore]], baseada na síntese viral de [[RNA mensageiro]].<ref name="pmid4329869">{{cite journal|author=Baltimore D|title=Expression of animal virus genomes|journal=Bacteriol Rev|volume=35|issue=3|pages=235–41|year=1971|pmid=4329869|doi=|url=http://mmbr.asm.org/cgi/pmidlookup?view=long&pmid=4329869}}</ref> O sistema agrupa os vírus em famíliassete classes dependendo do seu genoma ([[DNA]], [[RNA]], fita dupla, fita simples) e de sua [[replicação do DNA|replicação de DNA]].
 
== Classificações ==
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<!--Classifying viruses according to their genome means that those in a given category will all behave in much the same way, which offers some indication of how to proceed with further research. In short:-->
 
*I: '''[[dsDNA virus]]''': [[vírus DNA]] fita dupla (e.g. ''[[Adenovirus]]'', ''[[Herpesvirus]]'', ''[[Poxvirus]]'')
*II: '''[[ssDNA virus]]''': (+)sensevírus DNA fita simples (e.g. ''[[Parvovirus]]'')
*III: '''[[dsRNA virus]]''': [[vírus RNA]] fita dupla (e.g. ''[[Reovirus]]es'')
*IV: '''[[positive-sense ssRNA virus|(+)ssRNA virus]]''': (+)sensevírus RNA fita simples positivo (e.g. ''[[Picornavirus]]'', ''[[Togavirus]]'')
*V: '''[[negative-sense ssRNA virus|(−-)ssRNA virus]]''': (−)sensevírus RNA fita simples negativo (e.g. ''[[Orthomyxovirus]]'', ''[[Rhabdovirus]]'')
*VI: '''[[ssRNA-RT virus]]''': (+)sensevírus RNA withfita DNAsimples intermediatecom inDNA life-cycleintermediário (e.g. ''[[Retrovirus]]'')
*VII: '''[[dsDNA-RT virus]]''': vírus DNA fita simples com RNA intermediário (e.g. ''[[Hepadnavirus]]'')
<!--
=== Classe I: Vírus DNA de fita dupla ===
 
ThisEste typetipo ofde virusvírus usuallygeralmente mustdeve enteringressar the hostno [[Cellnúcleo nucleuscelular|nucleusnúcleo]] beforedo hospedeiro antes itque isseja ablecapaz tode replicatereplicar. Além Furthermoredisso, theseestes virusesvírus requirerequerem hostcélulas cellcom [[DNA polymerasepolimerase|polymerasespolimerases]] topara replicatereplicar the viralo [[genomegenoma]] andviral hencee, areportanto, highlysão dependentaltamente ondependentes thedo [[cellciclo cyclecelular]]. A Properinfecção infectione andprodução productionde ofprogênie progenyexige requiresque thatas thecélulas cellestejam beem inreplicação, replicationmomento asem thatque isas whenpolimerases theestão cell's polymerases are activeativas. O The virus mayvírus inducepode theforçar cella tocélula forcefullya undergosofrer [[celldivisão divisioncelular]], ande chronicallycronicamente, thisisto maypode leadlevar toa [[celltransformação transformationcelular|transformationtransformação]] ofda thecélula celle, and ultimately,até [[cancercâncer]]. Examples includeFamílias: [[Herpesviridae]], [[Adenoviridae]] ande [[PapovaviridaePolyomaviridae]].
 
=== Classe II: Vírus DNA de fita simples ===▼
There is only one well studied example in which a class 1 virus is not replicating within the nucleus, that is the [[Poxvirus]] family, a highly pathogenic virus that infects [[vertebrate]]s and includes the [[smallpox]] virus.
 
Inclui vírus não muito bem estudados, mas com grande poder de infecção para os vertebrados. Replicam dentro do núcleo e formam um DNA de fita dupla intermediário durante a replicação. Famílias: [[Circoviridae]] e [[Parvoviridae]].
▲=== Classe II: Vírus DNA de fita simples ===
 
=== Classe III: Vírus RNA de fita dupla ===▼
Viruses that fall under this category include ones that are not as well studied, but still pertain highly to vertebrates. Two examples include the [[Circoviridae]] and [[Parvoviridae]]. They replicate within the nucleus and form a double stranded DNA intermediate during replication. A prevalent but [[asymptomatic]] human Circovirus called [[Transfusion Transmitted Virus]] (TTV) is included within this classification.
 
Como a maioria dos [[vírus RNA]], essa classe se replica no [[citoplasma]], não necessitando das polimerases do hospedeiro como ocorre nos [[vírus DNA]]. Este grupo também não é bem estudado, e inclui duas grandes famílias, a [[Reoviridae]] e [[Birnaviridae]]. A replicação é monocistrônica e inclui genomas individuas e segmentados, significando que cada gene codifica apenas uma protéina, ao contrário de outros vírus que exibem tradução mais complexa.
▲=== Classe III: Vírus RNA de fita dupla ===
 
=== Classe IV & V: Vírus RNA de fita simples ===▼
As with most [[RNA]] viruses, this class replicates in the [[cytoplasm]], not having to use the host replication polymerases to as much a degree as [[DNA]] viruses. This family is also not as well studied as the rest and includes 2 major families, the [[Reoviridae]] and [[Birnaviridae]]. Replication is [[monocistronic]] and includes individual, segmented genomes, meaning that each of the genes code for only one protein, unlike other viruses which exhibit more complex translation.
 
Estes vírus consistem de dois tipos, entretanto, ambos compartolham o fato que a replicação é principalmente no citoplasma, e que esta replicação não é dependende do ciclo celular. Compreende vírus muito bem estudados.
▲=== Classe IV & V: Vírus RNA de fita simples ===
 
==== Classe IV: Vírus RNA de fita simples - Positive (+)senso sensepositivo ====▼
These viruses consist of two types, however both share the fact that replication is primarily in the cytoplasm, and that replication is not as dependent on the cell cycle as other DNA viruses. This class of viruses is one of the best studied, alongside the double stranded DNA viruses.
 
▲==== Classe IV: Vírus RNA de fita simples - Positive (+) sense ====
 
The positive sense RNA viruses and indeed all genes defined as '''[[positive sense]]''' can be directly accessed by host polymerases to immediately form proteins. These can be divided into two groups, both of which reproduce in the cytoplasm:
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Examples of this class include the families [[Astroviridae]], [[Caliciviridae]], [[Coronaviridae]], [[Flaviviridae]], [[Picornaviridae]], [[Arteriviridae]] and [[Togaviridae]].
 
==== Classe V: Vírus RNA de fita simples - Negative (-)senso sensenegativo ====
 
The negative sense RNA viruses and indeed all genes defined as '''[[negative sense]]''' cannot be directly accessed by host polymerases to immediately form proteins. Instead, they must be [[transcription (genetics)|transcribed]] by viral polymerases into a "readable" form, which is the positive sense reciprocal. These can also be divided into two groups:
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Examples in this class include the families [[Arenaviridae]], [[Orthomyxoviridae]], [[Paramyxoviridae]], [[Bunyaviridae]], [[Filoviridae]] and [[Rhabdoviridae]] (the latter which includes [[rabies]]).
 
=== Classe VI: Positivevírus (+)RNA sensefita singlesimples strandedsenso RNApositivo virusesque thatreplica replicateatravés throughde aum DNA intermediateintermediário ===
 
A well studied family of this class of viruses include the [[Retroviridae|retroviruses]]. One defining feature is the use of [[reverse transcriptase]] to convert the positive sense RNA into DNA. Instead of using the RNA for templates of proteins, they use DNA to create the templates, which is spliced into the host genome using [[integrase]]. Replication can then commence with the help of the host cell's polymerases. A well studied example includes [[HIV]].
 
=== Classe VII: Double strandedvírus DNA virusesfita thatdupla replicateque thoughreplica aatravés singlede strandedum RNA intermediatefita simples intermediário ===
 
Este pequeno grupo de vírus
 
This small group of viruses, exemplified by the [[Hepatitis B]] virus (which is in the [[Hepadnaviridae]] family), have a double-stranded, gapped genome that is subsequently filled in to form a covalently closed circle ([[ccc DNA]]) that serves as a template for production of viral [[mRNA]]s and a [[subgenomic]] RNA. The pregenome RNA serves as template for the viral reverse transcriptase and for production of the DNA genome.
Obtida de "https://pt.wikipedia.org/wiki/Classificação_de_Baltimore"