flu Antibody
Description
Introduction to Flu Antibodies
Flu antibodies are immune proteins produced in response to influenza virus infections or vaccinations. They bind to antigenic sites on viral surface proteins—hemagglutinin (HA) and neuraminidase (NA)—to neutralize infection or mitigate disease severity. These antibodies are critical for understanding vaccine efficacy and therapeutic interventions, as demonstrated by antigenic characterization studies and clinical trials .
Types of Flu Antibodies and Their Targets
Flu antibodies can be broadly categorized by their binding regions and functional mechanisms:
Hemagglutinin (HA)-Specific Antibodies
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HA Head Antibodies:
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HA Stem Antibodies:
Neuraminidase (NA)-Specific Antibodies
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NA Head Antibodies:
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NA "Dark Side" Antibodies:
Mechanisms of Action
Flu antibodies neutralize viruses through direct and indirect mechanisms:
Monoclonal Antibodies
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CR9114:
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1G01:
Antibody-Based Therapies
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Flu-IVIG (Intravenous Immunoglobulin):
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VIR-2482:
Vaccines
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mRNA-1010:
Challenges and Future Directions
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Antigenic Drift/Shift: HA head antibodies’ limited cross-reactivity necessitates annual vaccine updates .
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NA Antibody Dynamics: NA-specific immunity is less understood but critical for reducing transmission .
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Therapeutic Gaps: No approved antibody therapies exist for influenza A, highlighting the need for broadly protective candidates like CR9114 or 1G01 .
Product Specs
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
The polyclonal flu antibody production involves a multi-step process. First, the recombinant Escherichia coli (strain K12) flu protein (amino acids 804-1039) is selected as the immunogen. This immunogen is administered to a rabbit through injections, repeated several times to elicit an immune response. Subsequently, the rabbit's B cells produce a significant amount of antibodies, primarily of the IgG isotype. These antibodies are then harvested from the rabbit serum and purified using protein G affinity chromatography. The flu antibody possesses the ability to react with the flu protein derived from Escherichia coli (strain K12). The purified flu antibody has been rigorously validated through ELISA and Western blot applications.
Escherichia coli flu protein (Ag43) is a phase-variable outer membrane protein playing a crucial role in the autoaggregation, flocculation, and colony morphology of E. coli K12 strains [1-4]. Ag43-mediated aggregation is macroscopically observable as cell flocculation in liquid suspensions [5]. Furthermore, Ag43 has been implicated in promoting the persistence of uropathogenic E. coli isolates within the urinary tract, underscoring its significance in bacterial virulence and pathogenesis [6]. Research has demonstrated that Ag43 facilitates specific bacterial uptake and survival within human neutrophils, highlighting its role in bacterial evasion of the host immune response [5].
References:
[1] Schembri, M., & Klemm, P. (2001). Coordinate gene regulation by fimbriae-induced signal transduction. The Embo Journal, 20(12), 3074-3081. https://doi.org/10.1093/emboj/20.12.3074
[2] Klemm, P., Hjerrild, L., Gjermansen, M., & Schembri, M. (2003). Structure‐function analysis of the self‐recognizing antigen 43 autotransporter protein from escherichia coli. Molecular Microbiology, 51(1), 283-296. https://doi.org/10.1046/j.1365-2958.2003.03833.x
[3] Krisandi, G., & Prayogo, S. (2021). Analisis potensi nanopartikel seng oksida sebagai terapi alternatif terhadap uropathogenic escherichia coli penyebab infeksi saluran kemih. Jimki Jurnal Ilmiah Mahasiswa Kedokteran Indonesia, 9(1), 38-47. https://doi.org/10.53366/jimki.v9i1.278
[4] Henderson, I., Meehan, M., & Owen, P. (1997). Antigen 43, a phase-variable bipartite outer membrane protein, determines colony morphology and autoaggregation in escherichia coli k-12. Fems Microbiology Letters, 149(1), 115-120. https://doi.org/10.1111/j.1574-6968.1997.tb10317.x
[5] Fexby, S., Bjarnsholt, T., Jensen, P., Roos, V., Høiby, N., Givskovet al. (2007). Biological trojan horse: antigen 43 provides specific bacterial uptake and survival in human neutrophils. Infection and Immunity, 75(1), 30-34. https://doi.org/10.1128/iai.01117-06
[6] Lüthje, P., & Brauner, A. (2010). Ag43 promotes persistence of uropathogenic escherichia coli isolates in the urinary tract. Journal of Clinical Microbiology, 48(6), 2316-2317. https://doi.org/10.1128/jcm.00611-10
Target Background
- In the K-12 leader sequence, two in-frame translation initiation codons have been identified, one upstream and the other downstream of the transcription terminator. For optimal agn43 expression, both codons need to be present. PMID: 24837285
- Lrp and MqsR, previously identified as agn43 regulators, do not regulate agn43 expression or ON/OFF switch frequency. PMID: 24039985
- The data support a model where, in an ON-phase cell, the subcellular availability of OxyR at the replication fork as it passes through the agn43 regulatory region is crucial for initiating an ON-to-OFF switch. PMID: 20118257
- The glycosylated form of Ag43 enhances bacterial binding to human cell lines. PMID: 16484190
- In vivo, the H107A substitution in sigma(32) hinders recovery from heat shock (exposure to 42 degrees C). Additionally, it leads to overexpression of the Flu protein at lower temperatures (30 degrees C), which is associated with biofilm formation. PMID: 17921304
- Glycosylation is likely to play significant roles in the structural and functional properties of bacterial autotransporters Ag43 at various levels. PMID: 18341480
- This review summarizes the proposed roles of Ag43 expression and places the studies into perspective considering the role of allelic variants, the genetic background of the bacterial strain, and the control of expression by phase variation. PMID: 18785838
- The authors demonstrate that Ag43 mediates bacterial adhesion in a cell line-specific manner, and structural variations in the alpha(43) domain correlate with enhanced adhesive properties to proteins of the extracellular matrix, such as collagen and laminin. PMID: 19230760
KEGG: ecj:JW1982
STRING: 316385.ECDH10B_2146
