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Showing posts from May 15, 2025

Molecular basis of #influenza #ribonucleoprotein complex #assembly and processive #RNA synthesis

Abstract Influenza viruses replicate and transcribe their genome in the context of a conserved ribonucleoprotein (RNP) complex . By integrating cryo–electron microscopy single-particle analysis and cryo–electron tomography , we define the influenza RNP as a right-handed, antiparallel double helix with the viral RNA encapsidated in the minor groove . Individual nucleoprotein subunits are connected by a flexible tail loop that inserts into a conserved pocket in its neighbor. We visualize the viral polymerase in RNP at different functional states , revealing how it accesses the RNA template while maintaining the double-helical architecture of RNP by strand sliding. Targeting the tail loop binding interface, we identify lead compounds as potential anti-influenza inhibitors . These findings elucidate the molecular determinants underpinning influenza virus replication and highlight a promising target for antiviral development. Source: Science,  https://www.science.org/doi/10.1126/science...

#Statement on the #antigen #composition of #COVID19 #vaccines (#WHO, May 15 '25)

  Key points -- Vaccination remains an important public health countermeasure against COVID-19 . As per the WHO Director General’s standing recommendations for COVID-19, Member States are recommended to continue to offer COVID-19 vaccination based on the recommendations of the WHO Strategic Advisory Group of Experts on Immunization (SAGE). -- SARS-CoV-2 continues to undergo sustained evolution since its emergence in humans, with important genetic and antigenic changes in the spike protein. -- The objective of an update to COVID-19 vaccine antigen composition is to enhance vaccine-induced immune responses to circulating SARS-CoV-2 variants. -- The WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) advises manufacturers that monovalent JN.1 or KP.2 vaccines remain appropriate vaccine antigens ; monovalent LP.8.1 is a suitable alternative vaccine antigen . -- In accordance with WHO SAGE policy, vaccination should not be delayed in anticipation of access to vacci...

Genetic diversity of #H5N1 avian #influenza viruses isolated from #birds and #seals in #Russia in 2023

Abstract Thousands of outbreaks of the highly pathogenic avian influenza A(H5N1) virus in birds and an increasing number of mammal infections are registered annually. In 2023, multiple avian influenza outbreaks were registered among wild birds, poultry and seals in Russia . The genetic characterization of seventy-seven avian viruses and three viruses from seals showed that they belonged to the 2.3.4.4b clade and represented four distinct reassortant genotypes . The majority of viruses represented genotype BB , which was widespread in Europe in 2023. Viruses from seals and four viruses from birds , isolated from outbreaks in the Far East region , belonged to the G1 (A3) genotype and had the amino acid substitution N319K in the NP protein , previously associated with an increased virulence for mammals . In addition, one virus of the G10 genotype and two viruses, representing a previously undescribed genotype (designated as Ru-23-G4) were identified. The viruses analyzed showed normal inh...

#Investigation of #Influenza #H5N1 Virus #Neutralization by Quadrivalent Seasonal #Vaccines, #UK, 2021–2024

Abstract We tested cross-neutralization against highly pathogenic avian influenza A(H5N1) virus in adults vaccinated with 2021–2023 seasonal quadrivalent influenza vaccine in the United Kingdom. Seasonal quadrivalent influenza vaccines are unlikely to protect vulnerable persons against severe H5N1 disease during widespread transmission. Enhanced measures are needed to protect vulnerable people from H5N1 virus infection. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/6/24-1796_article ____