वायरस
वायरस चाहे वाइरस () बहुत सूछ्म आकार के रोगकारी होलें जे इन्फेक्शन करे लें आ कौनों जिंदा जीवधारी के कोशिका (सेल) में आपन संख्या बढ़ावे लें। वायरस सभ कौनो भी किसिम के जीवधारी के शरीर में प्रवेश क के इन्फेक्शन क सके लें, एह में जानवर आ पेड़-पौधा से ले के सूछ्मजीव सभ जइसे कि बैक्टीरिया आ आर्काइया भी शामिल बाड़ें जे इनहना से परभावित हो सके लें।

जब दमित्री इवानोव्सकी के 1892 के लेख में बैक्टीरिया के अलावा दुसरे किसिम के रोगकारी के बारे में छपल जवना से तमाकू के पौधा परभावित होखे आ एकरे बाद मार्टिनस बेइजरिंक 1898 में टोबैको मोजैक वायरस के पहिचान कइलें तबसे ले के अबतक ले 5,000  से बेसी वायरस प्रजाति सभ के बिस्तृत बिबरन दिहल जा चुकल बाटे, जबकि पर्यावरण में कई लाख किसिम के वायरस मौजूद बाड़ें। वायरस पृथ्वी के लगभग हर किसिम के इकोसिस्टम में पावल जालें आ ई जीव जगत के सदस्य सभ में सभसे बेसी के संख्या वाला प्रकार हवे। वायरस के अध्ययन करे वाली शाखा के वाइरोलॉजी भा वायरोलॉजी कहल जाला जे माइकोबायोलॉजी (सूछ्मजीवबिज्ञान) के उपशाखा हवे।

बर्गीकरण

Classification seeks to describe the diversity of viruses by naming and grouping them on the basis of similarities. In 1962, André Lwoff, Robert Horne, and Paul Tournier were the first to develop a means of virus classification, based on the Linnaean hierarchical system. This system based classification on phylum, class, order, family, genus, and species. Viruses were grouped according to their shared properties (not those of their hosts) and the type of nucleic acid forming their genomes. In 1966, the International Committee on Taxonomy of Viruses (ICTV) was formed. The system proposed by Lwoff, Horne and Tournier was never fully accepted by the ICTV because small genome size viruses and their high rate of mutation makes it difficult to determine their ancestry beyond order. As such, the Baltimore classification is used to supplement the more traditional hierarchy.

ICTV classification 
The International Committee on Taxonomy of Viruses (ICTV) developed the current classification system and wrote guidelines that put a greater weight on certain virus properties to maintain family uniformity. A unified taxonomy (a universal system for classifying viruses) has been established.  Only a small part of the total diversity of viruses has been studied.

The general taxonomic structure of taxon ranges actually used (as of November 2018) is as follows:

Phylum (-viricota)
Subphylum (-viricotina)
Class (-viricetes)
Order (-virales)
Suborder (-virineae)
Family (-viridae)
Subfamily (-virinae)
Genus (-virus)
Subgenus (-virus)
Species

As of 2018, 14 orders, 143 families, 64 subfamilies, 846 genera, and 4,958 species of viruses have been defined by the ICTV. The orders are the Caudovirales, Herpesvirales, Ligamenvirales, Mononegavirales, Nidovirales, Ortervirales, Picornavirales, Bunyavirales, Tymovirales, Muvirales, Serpentovirales, Jingchuvirales, Goujianvirales, and Articulavirales.

Baltimore classification 

The Nobel Prize-winning biologist David Baltimore devised the Baltimore classification system. The ICTV classification system is used in conjunction with the Baltimore classification system in modern virus classification.

The Baltimore classification of viruses is based on the mechanism of mRNA production. Viruses must generate mRNAs from their genomes to produce proteins and replicate themselves, but different mechanisms are used to achieve this in each virus family. Viral genomes may be single-stranded (ss) or double-stranded (ds), RNA or DNA, and may or may not use reverse transcriptase (RT). In addition, ssRNA viruses may be either sense (+) or antisense (−). This classification places viruses into seven groups:

As an example of viral classification, the chicken pox virus, varicella zoster (VZV), belongs to the order Herpesvirales, family Herpesviridae, subfamily Alphaherpesvirinae, and genus Varicellovirus. VZV is in Group I of the Baltimore Classification because it is a dsDNA virus that does not use reverse transcriptase.

The complete set of viruses in an organism or habitat is called the virome; for example, all human viruses constitute the human virome.

संदर्भ

स्रोत ग्रंथ

 Collier, Leslie; Balows, Albert; Sussman, Max (1998) Topley and Wilson's Microbiology and Microbial Infections ninth edition, Volume 1, Virology, volume editors: Mahy, Brian and Collier, Leslie. Arnold. .
 Dimmock, N.J; Easton, Andrew J; Leppard, Keith (2007) Introduction to Modern Virology sixth edition, Blackwell Publishing, .
 Knipe, David M; Howley, Peter M; Griffin, Diane E; Lamb, Robert A; Martin, Malcolm A; Roizman, Bernard; Straus Stephen E. (2007) Fields Virology, Lippincott Williams & Wilkins. .
 Shors, Teri (2008). Understanding Viruses. Jones and Bartlett Publishers. .

 
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