Difference Between Streptolysin O and Streptolysin S

Key Difference – Streptolysin O vs Streptolysin S
 

Streptolysin is considered as a streptococcal hemolytic exotoxin. In simple terms, it is the hemolysin produced by Streptococcus bacteria. Hemolysins are compounds that could be lipids or proteins that have the potential to cause the destruction of red blood cells through lysis. There are different streptolysin types such as streptolysin O (SLO), streptolysin S (SLS), etc. Streptolysin O is active only during conditions of reversibly reduced states and Streptolysin S is stable during conditions where oxygen is present at higher concentrations. Therefore, streptolysin O is considered as oxygen labile and streptolysin S is considered as oxygen stable. This is the key difference between Streptolysin O and Streptolysin S.

CONTENTS

1. Overview and Key Difference
2. What is Streptolysin O
3. What is Streptolysin S
4. Similarities Between Streptolysin O and Streptolysin S
5. Side by Side Comparison – Streptolysin O vs Streptolysin S in Tabular Form
6. Summary

What is Streptolysin O?

Streptolysin O (SLO) is a compound that is oxygen labile. In other terms, Streptolysin O is active only during conditions of reversibly reduced states. It contains antigenic properties. Compared to Streptolysin S, Streptolysion O is larger in size. That is one of the major reason why it contains antigenic properties. With regards to its function, Streptolysin O mainly affects the breaking of red blood cells (hemolysis). Similar to streptolysin S, streptolysin O is considered as streptococcal hemolytic exotoxin that is mostly produced by the Group A Streptococcus. Targeted cells of the streptolysin O are myocardial cells, epithelial cells, platelets, and neutrophils.

The antibody that is produced against streptolysin O is antistreptolysin O (ASO). ASO is produced when the body gets infected with the disease condition. During such infectious conditions, the body produces different types of antibodies against the antigens of Streptococcus.  Therefore, ASO is a type of antigen produced. The elevated levels of ASO indicate the occurrence of past or present infection. This ASO was used as the marker during early days of infection during the diagnosis process of rheumatic fever. The production of the antibody occurs as a response to the exposure towards the pathogen. But during some conditions, the patient might be asymptomatic even after exposing to the bacteria and not producing ASO.

What is Streptolysin S?

Streptolysin S is an oxygen stable hemolysin produced by Streptococcus species. Streptolysin S is not considered as an antigenic component due to its small size, which is roughly 2.8 kDa. It is also referred to as cardiotoxic exotoxin, that is a type of beta-hemolytic component. Streptolysin S is a type of potent cell poison that has the potential to affect different types of cells including platelets, neutrophils, etc. These hemolysins could also affect the subcellular organelles. Other than these types of target cells streptolysin S have the ability to induce cytotoxic effects on myocardial cells and epithelial cells.

Streptolysin S a major type streptolysin that is responsible for the phenotype of the characteristic beta hemolysis of group A streptolysin (GAS). This involves as a contribution for pathogenesis that occurs through the modulation of host immune response that takes place during the early stage of the development of the infection. Also, inhibition of neutrophil opsonophagocytosis mainly contributes towards the pathogenesis process.

What are the Similarities Between Streptolysin O and Streptolysin S?

• Both Streptolysin O and Streptolysin S are hemolysins produced by Streptococcus spp.
• Both Streptolysin O and Streptolysin S are virulence factors.

What is the Difference Between Streptolysin O and Streptolysin S?

Summary – Streptolysin O vs Streptolysin S

Streptolysin is a streptococcal hemolytic exotoxin. In simple terms, it is the hemolysin produced by Streptococcus bacteria. In the context of different streptolysin types, streptolysin O (SLO) and streptolysin S (SLS) are two types. Streptolysin O (SLO) is a compound that is oxygen labile. In other terms, Streptolysin O is active only during conditions of reversibly reduced states. The antibody that is produced against streptolysin O is anti-streptolysin O (ASO). ASO is produced when the body gets infected with the disease condition. Streptolysin S is an oxygen stable hemolysin produced by Streptococcus species. Streptolysin S is not considered as an antigenic component due to its small size. This is the difference between Streptolysin O and Streptolysin S.

Reference:

1.Reglinski, Mark, and Shiranee Sriskandan. “Streptococcus pyogenes.” Molecular Medical Microbiology, 2015, pp. 675–716., doi:10.1016/b978-0-12-397169-2.00038-x
2.Bhakdi, S, et al. “Mechanism of membrane damage by streptolysin-O.” Infection and Immunity, U.S. National Library of Medicine, Jan. 1985. Available here 

Image Courtesy:

1.’Group A Streptococcus Bacteria on Human Neutrophil (8517040030)’By NIAID (CC BY 2.0) via Commons Wikimedia