SARS-CoV-2 mutation becomes more contagious

More than 47.3 million people worldwide are infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which causes COVID-19. The virus has killed more than 1.2 million people and the pandemic is currently showing no signs of waning. Many countries around the world, with fewer cases and recovering, are witnessing a second wave of infection, again urging a global blockade to break the chain of infection.

A team of researchers working with Scott Wesley Long of the Houston Methodist Hospital and colleagues in Texas, New York, and Illinois have studied the patterns of SARS CoV-2 gene mutations and their impact on the second wave of infections worldwide. did. Their study, “Early Transmission of SARS-CoV-2 Virus in Major Metropolitan Areas and Large-Scale Second Wave Molecular Structure,” was published in the latest issue of the journal. mBio..

Background

SARS-CoV-2 is highly infectious and spreads rapidly from person to person. In the United States (US), virus-spreading hotspots are located in areas such as Seattle and New York City (NYC), leading to the infection and death of thousands of people nationwide. By mid-August, the research team had “227,419 confirmed SARS-CoV-2 cases in New York, causing 56,831 hospitalizations, 19,005 confirmed deaths and an estimated 4,638 deaths. I wrote. In Seattle and King County, there were “17,989 positive cases and 696 deaths.”

Travel and COVID-19

According to the researchers, the main cases were found among people associated with domestic or international travel. This has led to the outbreak they wrote.

Genome mutation

The Houston region of Texas is one of the most ethnically diverse regions in the United States, witnessing thousands of cases. One of the central molecular diagnostic laboratories corresponds to the Houston Methodist Hospital, from which data can be obtained. The researchers were able to identify the genomic mutations that are causing the infection in the area, the researchers wrote.

Genome sequencing was performed to identify mutations in the viral strains causing infection around the region. Genome sequencing studies began in March and needed to be expanded by May when researchers realized that the first wave of infection had diminished and then a second wave was possible. ..

(A) COVID-19 cases confirmed in the Greater Houston metropolitan area. The data represent the cumulative number of COVID-19 patients up to July 7, 2020. The counties include Austin, Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery and Waller. The shaded areas represent the time period during which the viral genome characterized in this study was recovered from COVID-19 patients (shown as months / days along the x-axis). The red line represents the number of COVID-19 patients diagnosed at the Houston Methodist Hospital Molecular Diagnostic Institute. (B) Distribution of strains with either the Asp614 or Gly614 amino acid variant on the spike protein between the two waves of COVID-19 patients diagnosed at the Institute for Molecular Diagnosis, Houston Methodist Hospital. The large inset shows the major clade frequencies for the time frame investigated (shown as month-to-month-day along the x-axis).

Purpose of research

The study reported that different strains of the virus were introduced from the outside over and over again in the Houston area alone. They were able to determine this from genotypes that match the genotypes of viral strains present in genotypes in Europe, Asia, South America, and elsewhere in the United States.

Specific mutant strain

Researchers found that the strain detected in Houston had a Gly614 amino acid substitution in the spike protein. This increased the infectivity or infectivity of the virus and spread it rapidly from person to person, creating a second wave.

Patients detected with the Gly614 mutant were found to have high viral load in the nose and nasopharynx at diagnosis.

What was done?

This study included detailed genotyping of 5,085 SARS-CoV-2 strains that caused two infectious waves of COVID-19 disease in a large city in Houston, Texas. Ethical diversity has led to the choice of the region for this study. Researchers write that the area has 7 million inhabitants.

The results revealed that viruses with different genotypes were introduced multiple times independently into the Houston population. This may have been due to a trip. The overall result is as follows:

• Wave 1 is defined as a new case between 5^th March and 11th^th May 2020.Wave 2 is defined as a case between 12^th May and 7th^th July 2020.
• The strain detected in the second wave was likely to carry the Gly614 amino acid substitution of the spike protein.
• Gly614 polymorphism (D614G mutation) was found to increase viral infection and risk of transmission
• People with variant virus also had higher nasopharyngeal viral load when first diagnosed
• However, the modified virus was not found to be more virulent than the previous strain.
• The severity of the disease in people infected with the second wave was more due to the condition of the underlying disease or the genetic composition of the infected individual, rather than the genetic composition of the virus itself.
• The researchers also noted that the region of the gene encoding the spike protein was most susceptible to mutations. This can be very important as these proteins may be targeted by vaccines against COVID-19.

Conclusions and implications

The co-author of the Ilya Finkelstein study, an associate professor of molecular bioscience at the University of Texas at Austin, said the study “viruses are mutated by a combination of neutral drifts-this simply means random genetic changes. And don’t help or hurt the virus-and pressure from our immune system. “

Finkelstein also said, “The virus continues to mutate as it hits the world … Real-time surveillance efforts like ours ensure that global vaccines and therapies are always one step ahead. I will do it. ” James Masser, lead author of the Houston Methodist, explained in a statement:

Long and his fellow researchers conclude: “Our study is the first analysis of the molecular structure of SARS-CoV-2 in two metropolitan infectious waves. The findings will help us understand future origin, composition, and orbit. Waves, and the potential impact of host immune responses and treatments on the evolution of SARS-CoV-2. “