What happened to Mu, Lambda and Gamma, the coronavirus variants that have affected South America the most

What happened to Mu, Lambda and Gamma, the coronavirus variants that have affected South America the most

The Gamma, Mu and Lambda variants circulated in the first half of last year, mainly in South America. REUTERS/Diego Vara

The pandemic is not over yet and today the whole world is affected by the prevalence of the Omicron variant of the coronavirus and its sub-lines. Since the start of the public health emergency, more than 511 million people have been diagnosed and 6.2 million have died. Scientists are monitoring the evolution of Omicron today, but argue that what happened to other variants of the coronavirus must be taken into account to know how the evolution of the coronavirus has been and could be. Among other things, they are studying what happened to the Gamma, Mu and Lambda variants, which hit South America last year.

Each of the variants of the coronavirus has its particularities. In this case of the Lambda variant -conocida popularly as an Andean variant-, it was detected by first in Perú in August 2020 and was reported by the Organización Mundial de la Salud (OMS), that the classification as a variant of interés en junio Last year.

At this moment, Lambda was the driving force behind the second wave of COVID-19 in Peru, leading to the collapse of hospitals in some cities. It has also been detected in 30 other countries like Chile, Bolivia, Argentina, Mexico and found to be more contagious than Alpha and Gamma. However, Lambda has found limits to its spread.

During this time, the The Mu variant was detected by Colombia’s National Institute of Health in January last year and it was not designated as a variant of interest by the WHO until August. It has been detected in more than 20 countries. He had several worrying mutations that experts say could help him evade immune system defences.

The Lambda variant was detected in Peru, where it caused the collapse of some hospitals / EFE / Luis Ángel González / Archive

The Lambda variant was detected in Peru, where it caused the collapse of some hospitals / EFE / Luis Ángel González / Archive

As well the Gamma variant circulated, which was predominant in South American countries, such as Argentina, Uruguay and Brazil, between March and August of last year. Gamma – also known as the “P.1 lineage” – has been detected in Brazil and in people who arrived in Japan and stayed in Brazil. In January last year, the WHO classified Gamma as a variant of concern (although the Greek name was not used at the time). From August to December in South America, the circulation of the Delta variant increased, but it did not generate a large wave like in other parts of the world, such as Europe.

viewed by InfobaeCarolina Torres, from the National Coronavirus Genomic Surveillance Project of the Ministry of Science, Technology and Innovation in Argentina, commented: “Gamma, Muy and Lambda are variants of the coronavirus that have circulated in Latin America. They have not become predominant all over the world, as there are different factors. One of them relates to properties such as transmission capacity, among others, and the immune status of the population. In the case of Gamma, it was a concerning variant that has predominated in the second wave in South America over the past year”. Meanwhile, Lambda was predominant in Peru and Chile, and Mu was predominant in Colombia in some months last year.

Gamma was a variant of concern but did not become globally predominant like Omicron. “Our hypothesis – said Dr. Torres – is that Gamma has not become predominant in other regions because all the income of a population is not enough for a community circulation of the variant to develop. It is likely that various admissions of people with Gamma occurred in South American countries, but there were more limitations in connections to other regions. On the contrary, the Beta variant, detected in South Africa, hardly circulated in South America”.

One of the lessons learned, according to Dr. Torres, who is researcher in virology at the faculty of pharmacy and biochemistry from the University of Buenos Aires and Conicet, is that “the epidemiology of the countries of the South American region has an influence on the neighbors, as it happened with the circulation of Gamma, Lambda and Mu, independently of what happened in North America, Europe or other parts of the world”.

The geographical context, the connectivity between countries, the vaccination rate of the population, the policy of restricting international travel, have had an impact on the circulation of variants in South America/Archive

The geographical context, the connectivity between countries, the vaccination rate of the population, the policy of restricting international travel, have had an impact on the circulation of variants in South America/Archive

Meanwhile, for Dr. Humberto Debat, a researcher at the National Institute of Agricultural Technology, “in South America, the landscape of coronavirus variants was exceptional. The frequency of variants was different compared to other regions between March and August. from last year. At one point we had thought that the Alpha variant, detected in the UK, might progress to South America, but that didn’t happen. This means that the geographical context, the connectivity between countries, the vaccination rate of the population, the policy of restricting international travel, have had an impact on the circulation of variants in this region.”

Lambda rivaled Gamma, but didn’t gain as much traction. Both were in turn replaced by Delta and then Omicron, which became exclusive. “The Delta variant arrived and kicked the board in South America, and displaced the others. These are variants with particular biological properties, but this also influences when they appear and the restriction policies that govern at every moment,” recalled Dr. Debat.

In the United States, scientist Joseph Fauver, a genomic epidemiologist at the University of Nebraska Medical Center, conducted a study on the Mu variant, which has virtually disappeared from global circulation of the virus. But they think a lot can be learned about the evolution of the virus. “This virus has no incentive to stop adapting and evolving,” said Joel Wertheim, a molecular epidemiologist at the University of California, San Diego, US. “And seeing how he has done in the past will help prepare us for what he might do in the future.”

The Mu variant “had a few mutations that people were watching very closely,” said Mary Petrone, a genomic epidemiologist at the University of Sydney and co-author of the new Mu paper. Several of the mutations of its Spike protein were due to been documented in other immunological variants, such as Beta and Gamma.

The scientists compared the biological characteristics of Mu with those of Alpha, Beta, Delta, Gamma and the original virus. They found that Mu did not replicate any faster than any other variant, but was the most immunoevasive of the group, the most resistant to antibodies. than any other known variant, with the exception of Omicron, according to doctor Fauver, in dialogue with the newspaper New York Times.

By analyzing the genomic sequences of Mu samples collected around the world, the researchers pieced together the spread of the variant. They concluded that Mu likely appeared in South America in mid-2020. It then circulated for months before being detected.

A study was conducted on the Mu variant in the United States / EFE / Carlos Ortega

A study was conducted on the Mu variant in the United States / EFE / Carlos Ortega

Mu also presented another challenge. It turns out he has a type of mutation, known as a frameshift mutation, which is rare in coronavirus samples. These types of mutations were flagged as errors when scientists, including Dr. Fauver, attempted to upload their Mu sequences to GISAID, an international repository of viral genomes used to monitor new variants.

This complication led to delays in the public release of the Mu sequences. The researchers found that the time between collecting a virus sample from a patient and making it publicly available in GISAID was consistently longer for Mu cases than for Delta cases.

“The genome itself was essentially creating artificial surveillance loopholes,” said Dr. Fauver. “The result, at least in our experience, was that we didn’t get the data for weeks when we normally try to get it within days.”

Combine these surveillance flaws with Mu’s immune evasion, and the variant seemed ready to take off. But it didn’t happen like that. Scientists have found that Mu spread from South America and Central America to other continents, but did not circulate widely once it got there. “This indicates that this variant did not necessarily adapt to North American and European populations as we expected.” said Dr. Petrone. This was probably because Mu found himself competing with an even more capable variant: Delta. Delta wasn’t as adept at dodging antibodies as Mu, but she was more transmissible.

Understanding what factors contribute to the prevalence of variants helps to understand the evolution of the coronavirus and to make decisions / EFE / Gustavo Amador / Archive

Understanding what factors contribute to the prevalence of variants helps to understand the evolution of the coronavirus and to make decisions / EFE / Gustavo Amador / Archive

Another recent study suggested that in New York, the Gamma variant tended to perform better in neighborhoods with higher pre-existing immunity levels, in some cases because they were hit hard in the first wave of COVID-19. “We cannot see a new variant in a vacuum, because it arises in the shadow of all the variants that came before it,” said Dr. Wertheim, who was one of the study’s authors.

The clash of past variants reveals that success is highly context dependent. For example, New York City may have been the birthplace of the Iota variant, which was first detected in virus samples collected in November 2020. Even after the more transmissible Alpha variant arrived, Iota remained the dominant variant in the city for months before finally disappearing. But in Connecticut, where Iota and Alpha appeared in January 2021, things turned out differently. Alpha took off immediately and Iota didn’t stand a chance.

A similar pattern begins to develop with the multiple lineages of Ömicron. In the United States, BA.2.12.1, a subvariant first identified in New York, has taken off, while in South Africa, BA.4 and BA.5 are on the rise again.

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