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03.18.2013

DNA from HeLa cells is sequenced

HeLa cells viewed under a light microscope

Nature magazine reports that a German lab has sequenced the DNA of HeLa cells. Like cells from most tumors, there are multiple copies of many genes. Excerpt:

Previous work showed that HeLa cells, like many tumors, have bizarre, error-filled genomes, with one or more extra copies of many chromosomes. To get a closer look at these alterations, a team led by Lars Steinmetz, a geneticist at the EuropeanMolecular Biology Laboratory in Heidelberg, Germany, sequenced the popular ‘Kyoto’ version of the cell line and compared the sequence with that of a reference human genome. The team’s results are published in G3.

Steinmetz’s team confirmed that HeLa cells contain one extra version of most chromosomes, with up to five copies of some. Many genes were duplicated even more extensively, with four, five or six copies sometimes present, instead of the usual two. Furthermore, large segments of chromosome 11 and several other chromosomes were reshuffled like a deck of cards, drastically altering the arrangement of the genes.

Without the genome sequence of Lacks’ healthy cells or that of her original tumor, it is difficult to trace the origin of these alterations. Steinmetz points out that other cervical tumors have massive rearrangements on chromosome 11, so the changes in the HeLa cell may have contributed to Lacks’ tumor.

HeLa cells have been the subject of many biological studies as they are easy to culture and replicate very fast. The cells were originally isolated from an African American woman named Henrietta Lacks, and have been cultured for over 60 years. There is also a fascinating book about the origin of these cells called The Immortal Life of Henrietta Lacks.

03.15.2013

adults cured of HIV

HIV Medications

A new report in PLoS Pathogens reports that in 14 adults are have been functionally cured of HIV. This comes after a Mississippi baby was miraculously cured of HIV because of early treatment. Early antiretroviral treatment seems to be important in these cases as well. From a summary in The New Scientist:

Asier Sáez-Cirión of the Pasteur Institute’s unit for regulation of retroviral infections in Paris analysed 70 people with HIV who had been treated with antiretroviral drugs (ARVs) between 35 days and 10 weeks after infection – much sooner than people are normally treated.

All of the participants’ drug regimes had been interrupted for one reason or another. For example, some people had made a personal choice to stop taking the drugs, others had been part of a trial of different drug protocols.

Most of the 70 people relapsed when their treatment was interrupted, with the virus rebounding rapidly to pre-treatment levels. But 14 of them – four women and 10 men – were able to stay off of ARVs without relapsing, having taken the drugs for an average of three years.

The 14 adults still have traces of HIV in their blood, but at such low levels that their body can naturally keep it in check without drugs.

The 14 adults are not naturally resistant to HIV infection and are not currently taking any medication to control their HIV.

03.15.2013

CD4 cells are instrumental in controlling HIV infection

HIV medication

A report in Science discusses how a subset of CD4 cells could prevent HIV from destroying the immune system:

HIV preferentially invades T lymphocytes that have CD4 receptors on their surfaces. The resulting destruction of CD4 cells over a decade or so cripples the immune system and is the hallmark of AIDS. But the process takes many years because the central memory cell, a type of CD4+ T lymphocyte known in shorthand as T_cm, churns out clones of itself and can almost refill the body’s pool of CD4 cells as fast as HIV drains it. However, the downside is that some infected T_cm cells become reservoirs of latent virus that rekindle infection if antiretrovirals (ARVs) are stopped.

The report is based on a series of studies of HIV patients. In the first study 75 HIV patients were split into three different groups and received antiretroviral medications within 5 days of taking a blood test. When their blood was analyzed 24 weeks later, the level of HIV-infected T_cm cells was almost extremely low or undetectable. In another study researchers looked at why some patients were better able to protect their CD4+ cells without antiretroviral treatment:

The study compared nearly 300 infected people who had low levels of HIV in their blood, two-thirds of whom received treatment. The researchers found that elite controllers stood out in part because their T_cm cells downregulated a key receptor that HIV needs for entry and were less permissive to HIV infection. Conversely, Kitchen noted that people whose immune systems did not rebound even though ARVs controlled their infections had T_cm cells with impaired function.

Check the source link for more.