Influenza PA (224–233)

Product Name: Influenza PA (224–233)

Sequence One Letter Code: SSLENFRAYV

Sequence Three Letter Code: H-Ser-Ser-Leu-Glu-Asn-Phe-Arg-Ala-Tyr-Val-OH

Chemical Formula:C53H80N14O17

Molecular Weight: 1185.4

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Infection Disease Research

Source / Species: Influenza

Conjugation: Unconjugated

Code Nacres: NA.26

Application: This peptide corresponds to amino acids 224–233 of the influenza A virus polymerase acidic (PA) protein and represents an immunodominant CD8⁺ T-cell epitope. The epitope is presented by murine MHC class I molecules H-2Db and H-2Kb and elicits strong cytotoxic T-cell responses during influenza PR8 infection. Because of its well-defined immunogenic properties, this peptide is widely used in immunological studies examining antiviral T-cell responses and antigen recognition. It supports experiments investigating T-cell activation, epitope presentation, and immune memory formation. The peptide is also used in vaccine research and experimental models of influenza infection to evaluate host immune responses and mechanisms of viral immunity.

Current Research: The adaptive immune system plays a crucial role in controlling viral infections through the coordinated activity of antigen-specific T lymphocytes. Among these immune mechanisms, CD8⁺ cytotoxic T cells (CTLs) are particularly important because they recognize and eliminate virus-infected cells. Research on T-cell immunity often relies on well-defined viral epitopes that consistently trigger strong immune responses. One such epitope is the influenza A PA (224–233) peptide, derived from the polymerase acidic (PA) protein of the influenza virus. This peptide represents a well-characterized immunodominant CD8⁺ T-cell epitope and is widely used to investigate antiviral immunity and T-cell–mediated responses. Influenza A Virus and Cellular Immunity Influenza A virus is a major respiratory pathogen responsible for seasonal epidemics and occasional pandemics. While antibodies play a key role in neutralizing viral particles, cell-mediated immunity is essential for eliminating infected cells and limiting viral replication within host tissues. CD8⁺ T cells recognize short viral peptides presented on the surface of infected cells by major histocompatibility complex (MHC) class I molecules. When these T cells detect viral peptides bound to MHC molecules, they become activated and can destroy infected cells through cytotoxic mechanisms such as perforin and granzyme release. Understanding how CD8⁺ T cells recognize viral epitopes and develop memory responses is a central focus of immunological research, particularly in the context of influenza infection. The PA Protein and the 224–233 Epitope The polymerase acidic (PA) protein is one of the three subunits that form the influenza viral RNA polymerase complex, which is responsible for replication and transcription of the viral genome. Because this protein is highly conserved and abundantly expressed during infection, it provides multiple potential targets for T-cell recognition. The PA (224–233) peptide represents a short sequence derived from this protein that functions as a dominant epitope recognized by CD8⁺ T cells. During infection with the influenza A/PR8 strain, this peptide is processed and presented by murine MHC class I molecules, specifically H-2Db and H-2Kb. Once presented on the surface of infected cells, the peptide–MHC complex is recognized by antigen-specific CD8⁺ T cells. This interaction triggers a strong cytotoxic response that contributes to viral clearance. Immunodominance and T-Cell Activation The PA (224–233) peptide is considered immunodominant, meaning that it stimulates a particularly strong and frequent T-cell response compared with other viral epitopes. Immunodominant epitopes are valuable experimental tools because they allow researchers to reliably monitor antigen-specific T-cell populations during infection. In experimental models of influenza infection, this peptide can be used to stimulate antigen-specific CD8⁺ T cells in vitro, allowing researchers to measure T-cell proliferation, cytokine production, and cytotoxic activity. These assays help reveal how antiviral T-cell responses are generated, maintained, and regulated. Studying Antigen Presentation and T-Cell Recognition Because the PA (224–233) epitope is well characterized, it serves as a useful model for examining the processes of antigen processing and presentation. Viral proteins are first degraded into peptide fragments inside infected cells. These fragments are then transported into the endoplasmic reticulum, where they bind to MHC class I molecules before being displayed on the cell surface. Using this defined peptide, researchers can investigate how antigen-presenting cells load peptides onto MHC molecules and how T-cell receptors (TCRs) recognize peptide–MHC complexes. These studies provide insight into the molecular basis of antigen specificity and T-cell activation. Applications in Influenza Infection Models The PA (224–233) peptide is widely used in murine models of influenza infection, particularly those involving the PR8 strain. In these systems, the peptide can be used to track virus-specific CD8⁺ T cells during different stages of infection. Researchers frequently employ this epitope in experiments that analyze T-cell expansion, effector function, and contraction of immune responses after viral clearance. These studies have helped clarify how immune responses evolve during infection and how long-term immune protection develops. The peptide is also used to examine the formation of memory T cells, which are responsible for rapid and effective immune responses during subsequent encounters with the virus. Relevance to Vaccine and Immunity Research Because CD8⁺ T-cell responses contribute to protection against influenza, defined viral epitopes such as PA (224–233) are valuable tools in vaccine research. Scientists use this peptide to evaluate how different vaccination strategies influence the generation of antigen-specific T-cell immunity. Studying responses to this epitope can also help researchers understand the mechanisms that promote durable immune memory and cross-protective immunity against related viral strains. A Key Tool for Investigating Antiviral T-Cell Immunity The influenza A PA (224–233) peptide provides a well-established model antigen for studying the cellular immune response to viral infection. Its ability to elicit strong CD8⁺ T-cell responses and its defined presentation by murine MHC class I molecules make it particularly useful for experiments examining T-cell activation, antigen recognition, and immune memory formation. Through its application in infection models, immunological assays, and vaccine studies, this peptide continues to support research aimed at understanding the mechanisms of antiviral immunity and improving strategies to combat influenza virus infections.