HIV-1 and HIV-2 appear to package their RNA differently. HIV-1 will bind to any appropriate RNA. HIV-2 will preferentially bind to the mRNA that was used to create the Gag protein itself. Recombination
Two RNA genomes are encapsidated in each HIV-1 particle (see Structure and genome of HIV). Upon infection and replication catalyzed by reverse transcriptase, recombination between the two genomes can occur. Recombination occurs as the single-strand, positive-sense RNA genomes are reverse transcribed to form DNA. During reverse transcription, the nascent DNA can switch multiple times between the two copies of the viral RNA. This form of recombination is known as copy-choice. Recombination events may occur throughout the genome. Anywhere from two to 20 recombination events per genome may occur at each replication cycle, and these events can rapidly shuffle the genetic information that is transmitted from parental to progeny genomes.Viral recombination produces genetic variation that likely contributes to the evolution of resistance to anti-retroviral therapy. Recombination may also contribute, in principle, to overcoming the immune defenses of the host. Yet, for the adaptive advantages of genetic variation to be realized, the two viral genomes packaged in individual infecting virus particles need to have arisen from separate progenitor parental viruses of differing genetic constitution. It is unknown how often such mixed packaging occurs under natural conditions.Bonhoeffer et al. suggested that template switching by reverse transcriptase acts as a repair process to deal with breaks in the single-stranded RNA genome.
Prostaglandins were discovered to be products of arachidonic acid and with the ability to radio label arachidonic acid in the early 1960s, American chemist E.J. Corey was able to synthesize prostaglandin E2 in the lab in the 1970. This advancement paved the way for later studies that helped define the actions and response of prostaglandin E2. Prostaglandin E2 was approved for medical use in the United States in 1977 and it is on the World Health Organizations List of Essential Medicines. Prostaglandin E2 was approved by the FDA in 1977. References
External links
"Dinoprostone". Drug Information Portal. U.S. National Library of Medicine.