Polyspermine-ribonuclease (Mr approximately 17 000) and the enzyme transcriptase from Rauscher-leukaemia virus (Mr approximately 70 000) form a complex Mr approx. 160 000) such that the molar ratio of polyspermine-ribonuclease to reverse transcriptase is 5:1. The most favourable condition for complex-formation is in a solution consisting of 0.01 M-Tris/HCl buffer, pH 7.5, 0.25 M-KCl and 1 mM-Mn...

3’-Azido-3’-deoxythymidine 5’4riphosphate (AZTTP) was an efficient substrate for the human immunodeficiency virus 1 reverse transcriptase. It was incorporated into both homopolymer and defined sequence DNA-primed RNA templates and DNA-primed DNA templates. The substrate and inhibitor kinetics of both AZTTP and dTTP were dependent on the template-primer and reaction conditions used. dTMP was inc...

ES cells. This phenomenon has been observed in our laboratory in a number of cases. Clones putatively identified as homologous recombinants by Southern analysis can be quickly checked for random insertion of extra copies of the targeting vector by PCR. Given the small difference in size between the two alleles and use of only two primers common to both WT and mutant DNA, the amplification rate ...

Within each viral particle, retroviruses package two copies of a single-stranded RNA genome of about 10 kb. All of the viral genomes contain three major genes, arranged in the order: 5 ́-gag–pol–env-3 ́, and some retroviruses may also have accessory genes (e.g. vif, vpr, tax, etc...). Structural proteins such as MA (matrix protein), CA (capsid protein) and NC (nucleocapsid protein) are encoded wi...

In 1961, Howard Temin began to gather evidence that was inconsistant with the central dogma. Temin, who devoted his life to studying RNA tumor viruses (now known as retroviruses), focused his early work on Rous sarcoma virus (RSV). This RNA virus is capable of transforming normal cells into cancerous cells. Temin felt the best explanation for the virus’s behavior was a model whereby the virus r...

I n the past two decades, intense efforts have been devoted to uncovering the mechanisms responsible for the maintenance of telomeres in eukaryotic cells. These efforts have led to the identification of an unusual reverse transcriptase (RT), named telomerase, that uses an integral RNA subunit as template to synthesize a short reiterated sequence at the ends of eukaryotic chromosomes (Fig. 1A) (...

Currently, 16 antiretroviral drugs are approved for treatment of HIV infection. However, even the best currently available regimens pose challenges with regard to adherence, toxicity, antiviral activity, and resistance. New drug development thus confronts the need for improved convenience and tolerability, reduced toxicity, and improved activity against both wild-type and drug-resistant viruses...

The reverse-transcriptase inhibitor lamivudine (Zeffix, GlaxoSmithKline) is often used to treat chronic infection with hepatitis B virus (HBV) until resistance develops. Treatment may then be switched to the reverse-transcriptase inhibitor adefovir (Hepsera, Gilead), which has a lower frequency of resistance. Here, we describe three cases of primary adefovir resistance that were sensitive to te...

Reverse transcriptase template switching has been invoked to explain several aspects of retroviral replication and recombination, and has been reported in vitro for the Moloney murine leukemia virus (M-MuLV) reverse transcriptase. During in vitro cDNA synthesis, the avian myeloblastosis virus (AMV) reverse transcriptase can switch from one template to another in a homology-dependent and tempera...