Influenza Virus Specific Neutra™ Antibody Products

Influenza viruses are RNA viruses causing contagious respiratory illnesses. Belonging to the Orthomyxoviridae family, they're classified into types A, B, C, and D. Types A and B drive seasonal epidemics in humans. The A-type viruses, including familiar strains like H1N1 and H3N2, derive their names from specific HA and NA surface proteins. While type C usually means mild symptoms, type D mostly bothers cattle and pigs. What makes type A stand out? It jumps between animal species and is the only type known to cause pandemics.

Genome and Structure

Influenza viruses feature a segmented, negative-sense, single-stranded RNA genome. Influenza A and B have eight segments. These encode 10 proteins. C and D have seven segments. These encode nine. Three segments encode RdRp, crucial for replication. The M1 matrix protein and M2 proton channel share a region, as well as NS1 and NEP. Each segment is vital to the virus's life cycle. HA and NA are encoded on separate segments in influenza A and B, whereas Influenza C and D encode HEF on one segment. The final segment encodes NP.

Fig. 1 Schematic representation of an influenza virus particle.^{1, 4}

The virion varies in shape, which is called pleomorphism. Clinical isolates are pleomorphic, whereas laboratory strains are spherical. The virion core contains a copy of each genome segment, which is bound to NP, forming RNPs. RdRp is bound to each RNP. The M1 matrix protein layer encapsulates this, supporting the outer lipid bilayer envelope. The envelope features HA and NA (or HEF) proteins for host cell attachment and viral release.

Influenza Virus Life Cycle

The influenza virus life cycle starts with HA-mediated attachment occurring at sialic acid receptors on host cells. The virus enters via endocytosis. In the endosome, acidic conditions trigger HA conformational changes, enabling the fusion of the viral and endosomal membranes. Viral RNA and proteins are then released into the cytoplasm.

Viral RNA gets transported to the nucleus and transcribed into mRNA by RdRp. The mRNA is translated into viral proteins in the cytoplasm. Newly synthesized HA, NA, and NP assemble with viral RNA. This forms new virus particles.

New virions assemble at the cell membrane. HA and NA are inserted into the cell membrane. Viral RNA and nucleoproteins form RNPs in the nucleus. RNPs are exported to the cytoplasm and migrate to the cell membrane. There, they bud off, releasing infectious virions. NA cleaves sialic acid, preventing aggregation and facilitating virus spread.

Fig. 2 Replication cycle of influenza virus.^{2, 4}

Influenza Virus Pathogenesis and Transmission

The virus zeroes in on our respiratory tract, triggering inflammation and tissue damage. Its spread mechanics are straightforward: infected droplets from coughs or sneezes either hang in the air we breathe or land on surfaces where they stay active for hours. Touch a contaminated doorknob then rub your eyes. That's another infection route. Symptoms typically hit fast - about two days post-exposure, though anywhere from 24 hours to four days. The classic package includes sudden fever, throat scratchiness, and deep fatigue. The severity of the infection is determined by the immune system's shape and the strain. For vulnerable groups like kids, seniors, and people with chronic conditions, things can turn dangerous fast with complications like lung infections or severe bronchitis.

Antibodies Targeting Influenza Virus

Antibodies are key to the immune response to influenza. The vital players here are neutralizing antibodies that can block the virus from latching onto cells or sabotage its replication process. These typically target those HA and NA proteins mentioned earlier. Researchers get particularly focused on broadly neutralizing antibodies - the special type forces that recognize multiple flu variants. These could revolutionize vaccine development. Recent advances include lab-made antibodies targeting HA's stem region and NA's active sites, showing promise against various strains. Beyond fighting infection, antibodies serve as detection tools - ELISA tests use them to identify viral particles in patient samples.

Fig. 3 Mechanism of NA inhibition by NA-specific antibodies.^{3, 4}

Creative Biolabs provides high-quality anti-influenza virus neutralizing antibody products for various applications, including ELISA, WB, FC, etc. With extensive experience, we deliver a broad portfolio, ensuring reliable results.

REFERENCES

1. Janssens, Yorick, et al. "The role of cell-mediated immunity against influenza and its implications for vaccine evaluation." Frontiers in Immunology 13 (2022): 959379.
2. Eichberg, Johanna, et al. "Antiviral potential of natural resources against influenza virus infections." Viruses 14.11 (2022): 2452.
3. Abbadi, Nada, and Jarrod J. Mousa. "Broadly protective neuraminidase-based influenza vaccines and monoclonal antibodies: Target epitopes and mechanisms of action." Viruses 15.1 (2023): 200.
4. Distributed under Open Access license CC BY 4.0, without modification.