New Strain Of HIV Under Group That Caused Pandemic

Scientists using advanced DNA sequencing technology have documented a previously unidentified strain of HIV under the group that is responsible for the vast majority of human infections. The previous strain in that group was documented in 2000. The latest strain was found in just three people, but the findings by Abbott Laboratories —a maker of HIV tests—are expected to strike up a broader conversation about how to classify new viral strains that could surface. The company described its findings on Wednesday in an academic journal.

Strains from Group M are the most common in humans and are responsible for the global AIDS pandemic. M strains have infected about 90% of the 37.9 million people that the World Health Organization estimated were living with HIV last year. Group O, N and P infections are rare but can also affect humans. Wednesday’s Abbott Labs findings have established a 10th group M strain. The three people who are known to carry it live in what is now the Democratic Republic of Congo, where the first HIV infection surfaced in a human in the mid-1900s. Decades later, the virus spread rapidly around the globe. Researchers and epidemiologists don’t expect the new Group M strain to change the way HIV is diagnosed or treated. Existing diagnostic tests and antiretroviral drugs, which suppress the growth of HIV, are designed to target the parts of the virus that are common to all groups. Still, they say new strains can offer clues on how HIV evolved and spread.

“There’s a lot of mystery around why certain things happened. New strains can unravel some of that unknown history,” said Brian Foley, an HIV geneticist at New Mexico’s Los Alamos National Laboratory, which holds the largest HIV gene bank and sets the guidelines on classifying new strains. Dr Foley wasn’t involved in Abbott’s research. Eventually, he says, the findings could help researchers engineer the Holy Grail in the fight against the virus: an HIV vaccine. The new Group M strain, called L, was detected by Abbott’s global surveillance program, which looks for unusual strains of HIV and hepatitis. The program helps the Illinois-based company keep its diagnostic tests up to speed. At least three samples are needed to establish a new HIV strain, according to guidelines set by the Los Alamos National Laboratory. Two samples of the L strain were detected in the Democratic Republic of Congo in 1983 and 1990. A third suspected sample was found by an Abbott partner hospital there in 2001. But sequencing technology at the time made it hard for company scientists in Illinois, where the sample was shipped, to read it accurately. “So this sample just sat in our fridge for years, waiting to be unlocked,” said Mary Rodgers, Abbott’s principal scientist and one of the authors of Wednesday’s report.

It was only in recent years, with the falling cost of DNA sequencing and the emergence of so-called next-generation sequencing technology, that Abbott scientists were able to isolate the viruses in the sample and read them. “What we were able to do is basically take a magnet and pull out the virus part of it,” said Dr Rodgers. The analysis confirmed the sample matched the unusual strain found in 1983 and 1990. Abbott doesn’t plan to offer a new diagnostic test based on the discovery but will make the DNA sequence of the new strain public so researchers can study it. Dr Foley says the Los Alamos National Laboratory plans to add “L” as a new strain in its database.

The finding is prompting a rethink of guidelines surrounding HIV. When they were established in 1999, Dr Foley says, decoding an entire genome was rare and the cost of sequencing was high. “One of the things we’re going to talk about next year is should you need, say, 30 samples instead of three to count as a new strain?” he said. Dr Foley is part of the committee that sets the rules. Another challenge for the committee is naming new strains. The 10 Group M strains are denoted by letters, while letters O, N and P denote other HIV groups. Either way, researchers say they will continue looking. “There’s a lot out there that we don’t know. This is really the tip of the iceberg,” said Abbott’s Dr Rodgers.

Credit: Preetika Rana for The Wall Street Journal, 6 November 2019.