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HIV
(CLICK TO PROCEED TO AIDS PAGE)

Retrovirus' Mechanism (VIDEO)

The video above briefly explains how retrovirus works, more importantly, how it functions.

http://www.youtube.com/watch?v=dn1tNIrMPRk

HTLV

HTLV is under the category of retroviruses which actually stands for Human T-lymphotropic virus.

http://www.fiocruz.br/

It is a human, single-stranded RNA retrovirus that causes T-cell leukemia and T-cell lymphoma in adults and may also be involved in certain demyelinating diseases, including tropical spastic paraparesis. Adult T-lymphotropic virus (ATLV) is a strain of this disease that affects primarily adults. A closely related virus is bovine leukemia virus BLV.

www.nature.com

Reference (retrovirus)

MAIN REFERENCE USED FOR RETROVIRUSES INFOs

References:
-Varmus, Harold E. "Form and Function of Retroviral Proviruses." Science 216, no. 4548 (1982): 812-820.

-Weinberg, Robert A. "How Cancer Arises." Scientific American 275, no. 3 (1996): 62-70.

accessed through www.answers.com/retrovirus

Infection (general info)

Consequences of Retroviral Infection

www.sciencedaily.com

Retroviral infection can result in several different outcomes for the virus and the cell. Retroviruses are capable of inducing immunosuppressive, autoimmune and neurological illnesses. Some retroviruses, such as the lentiviruses and the spumaviruses, are capable of directly killing cells. Cytopathic (cell-killing) effects in infected T cells and cells in the brain may account for the profound immune deficiencies and neurological diseases induced by HIV and related lentiviruses.

www.nature.com/.../n3/images/nrmicro1866-i1.jpg

Retroviruses are also capable of inducing latent infections, in which the virus is dormant, or persistent infections, in which low levels of the virus are continuously produced. These capabilities explain the life-long nature of retroviral infections, and render the diseases induced by these pathogens extremely difficult to treat.

Reverse Transcriptase

Reverse Transcriptase

Retroviruses’ replication cycle involves retroviral reverse transcriptase,

aids.about.com/.../ss/livecycle_4.htm

Reverse transcriptase - an enzyme which converts the single-stranded, positive-polarity RNA genome of retrovirus into double-stranded DNA, thereby reversing the typical flow of genetic information (which is from DNA to mRNA).

www.thebody.com/content/art14193.html

The DNA copy is transported into host cell’s nucleus, circularized and integrated into the host chromosome itslef.
This DNA copy of the retrovirus genome is called as “poxvirus or proviral DNA”. The genomes of most vertebrates contain abundant numbers of incomplete and complete proviruses (endogenous retroviruses) that appear to represent remnants of past retroviral infections in germline cells. Proviruses contain structures called long terminal repeats (LTR) at each end which contains promoter elements and transcriptional start sites that enable the retroviral genes to be expressed which can also affect the expression of nearby cellular genes.

Development & Classification

Development of retroviruses

Studies of retroviruses led to the first demonstrated synthesis of DNA from RNA templates, a fundamental mode for transferring genetic material that occurs in both eukaryotesand prokaryotes. It has been speculated that the RNA to DNA transcription processes used by retroviruses may have first caused DNA to be used as genetic material. In this model, the RNAworld hypothesis, cellular organisms adopted the more chemically stable DNA when retroviruses evolved to create DNA from the RNA templates.

Classification

Exogenous
The following genera are included here:

Alpharetrovirus - Avian leukosis virus
Betaretrovirus - Mouse mammary tumour virus
Gammaretrovirus - Murine leukemia virus, Feline leukemia virus
Deltaretrovirus - Bovine leukemia virus Human T-lymphotrophic virus
Epsilonretrovirus - Walleye dermal sarcoma virus
Lentivirus - Human Immunodeficiency virus 1, Simian and Felian Immunodeficiency viruses Spumavirus - Chimpanzee foamy virus

Characteristics

Characteristics

The classification of retroviruses is based on:
- comparisons of the size of the genome and
- morphologic characteristics (see Table 1).
RNA genome of retroviruses - single-stranded & possesses "positive" polarity similar to that found in messenger RNA (mRNA).
Virions (virus particles) contain two 5′ ("five prime"), end-linked, identical copies of the genome RNA, and are therefore said to be diploid.

Table 1

Brief Introduction

RETROVIRUS

















Retroviruses are RNA-containing viruses that uses enzyme, reverse transcriptase to copy their RNA into the DNA of a host cell.
Retroviruses have been isolated from a variety of vertebrate species, including humans, other mammals, reptiles, and fish. The family Retroviridae includes such important human pathogens as human immunodeficiency virus (HIV) and human Tlymphotropic virus (HTLV), the causes of AIDS and adult T-cell leukemia respectively. The study about this kind of virus led to the discovery of oncogenes, resulting in a quantum advance in the field of cancer genetics making Retro-viruses valuable research tools in molecular biology and gene therapy.
http://www.answers.com/retrovirus


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