#hiv replication

For decades, scientists have recognized that human immunodeficiency virus (HIV) is a formidable viral pathogen. After years of probing work and extensive experimentation, a Yale research team has unlocked one of the reasons why that is. In a new study, the lab led by immunologist Grace Chen discovered that HIV produces a circular RNA (circRNA) that helps the virus turn on its genes and replicate more efficiently. The discovery, which the researchers dubbed "circHIV," could represent a new target for future HIV therapies. The findings, described in the journal Nature Microbiology, follow a long journey for Chen, an assistant professor of immunobiology and of genetics at Yale School of Medicine. Her lab studies circRNAs, which differ from typical or linear RNAs in that they lack distinct, functional "ends." Unlike linear RNA, loop-shaped circRNAs are very stable. Chen began this project in 2019 with Prisca Obi, who at the time was her graduate student, and Lichong Yan, an associate research scientist and postdoc, who are the study's co-first authors. Given HIV's genetic makeup, Chen thought it would be a likely candidate to be generating circRNAs. She was right. How the new viral RNA was found. After first sequencing RNA from HIV-infected cells, the researchers discovered that HIV encodes circRNAs, including the abundantly expressed one that they name circHIV. They then detected the looped structures in infected human cells and in blood plasma from people living with HIV. Further experiments showed that by reducing levels of the circHIV it also lowered HIV gene activity, while adding extra circHIV increased it. Finally, protein-binding experiments revealed how the circHIV binds to the HIV Tat (Trans-Activator of Transcription) protein, explaining how it's able to boost viral transcription so readily. They gathered much of this key data in early 2020, before the research came to a halt with the arrival of the COVID-19 pandemic.

Gene Editing Technique Has Eliminated HIV Infection In Animals

After success in making cells resistant to HIV, another huge breakthrough has happened. Scientists from Temple University and the University of Pittsburgh used the revolutionary gene editing technology to eliminate HIV DNA from human cells implanted into mice. It is the first time scientists have ever achieved complete elimination in animal models, representing a significant step towards human clinical trials.

First Performance Of HIV Replication Ever

A stunning demonstration of HIV replication, first of its kind, scientists conducted based on their previous proof-of-concept study in which they managed to remove HIV-1 from the genome of most tissue. The concept includes testing three different animal models, one of which were mice transplanted with human cells and subsequently infected with the virus. One year later, the team managed to eliminate HIV from every tissue.

  Scientists have demonstrated that HIV-1 can be completely eliminated from infected cells in mice with a powerful gene editing technology

Dr. Wenhui Hu, an associate professor in the Center for Metabolic Disease Research and the Department of Pathology at Temple University, said in a press release: Our new study is more comprehensive. We confirmed the data from our previous work and have improved the efficiency of our gene editing strategy. We also show that the strategy is effective in two additional mouse models. One representing acute infection in mouse cells and the other representing chronic infection in human cells.

CRISPR – Powerful Gene Editing Technology

None of this wouldn’t be achieved without the use of an innovative gene-editing technique known as CRISPR. The technique works by guiding ‘scissor-like’ proteins to targeted sections of DNA within a cell and then prompting them to alter or ‘edit’ them in some way. So basically, if you want to edit the DNA of a virus within a human cell, you need a bacterium to go in, encounter the virus, and produce a strand of RNA that’s identical to the sequence of the virtual DNA.

Using this technique, researchers tested three groups of mice. One group was infected with HIV-1, the second were given an EcoHIV ( the equivalent of HIV-1) and the third were the ‘humanized’ mice which had been implanted with human immune cells, infected with HIV-1.

The results were impressing. After treating the first group, HIV was inactive and RNA expression of viral genes was reduced between 60 and 95 percent. In the second group, 96 percent of the EcoHIV was eliminated. And most important for us: after applying the CRISPR on the humanized mice, HIV was totally removed from the latently infected human cells in the mouse tissue and organs.

While this brings hope for a permanent cure for HIV infection, the team acknowledged that there’s still a long way to go before this particular strategy can be used on humans. The next step is to test the primates, and if the results are replicated, we can expect clinical trial on human patients.