The key difference between L and S coronavirus is that L coronavirus exhibits a ‘CT’ haplotype having the codon of Leucine at T28,144 while S coronavirus exhibits a ‘TC’ haplotype having the codon of Serine at C28,144.
Severe Acute Respiratory Syndrome Coronavirus 2 or SARS-CoV-2 is the causative agent of coronavirus disease – COVID 19. The virus was previously known as 2019 novel coronavirus. This virus is genetically closely related to the coronavirus responsible for the SARS outbreak of 2003. Hence, the novel coronavirus is named based on the relationship with SARS-CoV-1. COVID 19 is a respiratory disease which transmits via droplets and physical contact. The most common symptoms of COVID 19 are fever, dry cough, tiredness and shortness of breath.
Researchers in China have found out two strains of SARS-CoV-2 that are circulating among the human population. They are “L” and “S” types. These two strains are very similar to each other. L lineage is the major (approximately 70%) while S is the minor (approximately 30%). Both L and S lineages exhibit complete linkage between the two SNPs located at location 8,782 and 28,144.
CONTENTS
1. Overview and Key Difference
2. What is L Coronavirus
3. What is S Coronavirus
4. Similarities Between L and S Coronavirus
5. Side by Side Comparison – L vs S Coronavirus in Tabular Form
6. Summary
What is L Coronavirus?
L coronavirus is one of the two strains of SARS-CoV-2. It is found to be prevalent in the early stages of COVID 19 outbreak in Wuhan. L coronavirus originated from the older S coronavirus. This strain is more aggressive and is responsible for 70% of COVID 19 cases around the world.
Figure 01: SARS-CoV-2
L lineage exhibits a complete linkage between the two SNPs at location 8,782 (orf1ab: T8517C, synonymous) and 28,144 (ORF8: C251T, S84L). It exhibits a ‘CT’ haplotype since T28,144 is in the codon of Leucine. Furthermore, L lineage had accumulated a significantly higher number of derived mutations than S lineage.
What is S Coronavirus?
S coronavirus is the second lineage of SARS-CoV-2. It is the older version. It is believed that L type is derived from S type. S coronavirus accounts for approximately 30% COVID cases. S type strains continuously infect new patients because it is less severe, and people carry it for a longer time before taking medicines. Therefore, it increases the risk of transmission. Similar to L lineage, S lineage shows complete linkage in two SNPs. Moreover, it exhibits “TC” haplotype having codon of Serine in the C28,144.
What are the Similarities Between L and S Coronavirus?
- SARS-CoV-2 has evolved into two major lineages known as “L” and “S” types.
- Whole-genome comparisons further confirm the separation of the L and S lineages
- These strains indicate that the virus is mutating.
- Both L and S coronaviruses show complete linkage in SNPs at location 8,782 (orf1ab: T8517C, synonymous) and 28,144 (ORF8: C251T, S84L).
- Two lineages might have different rates in transmission or replication.
What is the Difference Between L and S Coronavirus?
L and S coronaviruses are two strains of SARS-CoV-2. L coronavirus is the more prevalent strain, which is one of the two strains of SARS-CoV-2. S coronavirus is a less severe strain of SARS-CoV-2. So, this is the key difference between L and S coronavirus. L coronavirus is responsible for about 70% cases while S coronavirus is responsible for about 30% cases.
Moreover, another difference between L and S coronavirus is that the L lineage exhibits a ‘CT’ haplotype while the S lineage exhibits a ‘TC’ haplotype.
The below infographic tabulates more differences between L and S coronavirus.
Summary – L vs S Coronavirus
L and S are two strains of SARS-CoV-2. They are more similar to each other. But, “L” coronavirus is more prevalent and is responsible for more than 70% of cases while “S” coronavirus is responsible for about 30% of the cases. Moreover, L lineage exhibits ‘CT” haplotype while S lineage exhibits a ‘TC’ haplotype. S lineage is evolutionary more related to animal coronaviruses. L lineage, on the other hand, had accumulated a significantly higher number of derived mutations than S lineage. Thus, this summarizes the difference between L and S coronavirus.
Reference:
1. McNamara, Alexander. “Coronavirus: Aggressive ‘L Type’ Strain Affecting 70 per Cent of Cases.” BBC Science Focus Magazine, 7 Apr. 2020, Available here.
2. Tang, Xiaolu, et al. “On the Origin and Continuing Evolution of SARS-CoV-2.” OUP Academic, Oxford University Press, 3 Mar. 2020, Available here.
Image Courtesy:
1. “SARS-CoV-2 without background” By CDC/ Alissa Eckert, MS; Dan Higgins, MAM – This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL) (Public Domain) via Commons Wikimedia