Related Experiment Video

Updated: Aug 16, 2026

Rapid Molecular Detection and Differentiation of Influenza Viruses A and B
05:38

Rapid Molecular Detection and Differentiation of Influenza Viruses A and B

Published on: January 30, 2017

Influenza A (H3N2) outbreak, Nepal

Luke T Daum1, Michael W Shaw, Alexander I Klimov

  • 1Air Force Institute for Operational Health, Brooks City Base, San Antonio, Texas 78235, USA. Luke.Daum@brooks.af.mil

Emerging Infectious Diseases
|August 17, 2005
PubMed

Insights

Influenza A (H3N2) viruses in Nepal showed significant antigenic drift from the 2004 vaccine strain. This viral evolution necessitated a vaccine strain update for the 2005-2006 influenza season.

Area of Science:

  • Virology
  • Epidemiology
  • Immunology

Background:

  • An influenza A (H3N2) outbreak occurred in Bhutanese refugee camps in Nepal in July 2004.
  • This outbreak provided an opportunity to study viral evolution and vaccine strain matching.

Purpose of the Study:

  • To investigate the antigenic properties of H3N2 influenza viruses isolated during the 2004 Nepal outbreak.
  • To compare these isolates with the contemporary A/Wyoming/3/03 vaccine strain.
  • To inform influenza vaccine strain selection for the subsequent season.

Main Methods:

  • Hemagglutination inhibition assays were used to assess antigenic distinctness.
  • Amino acid sequencing of viral isolates was performed.
  • Comparison of isolate sequences with the A/Wyoming/3/2003 vaccine strain.

Main Results:

  • Approximately 40% of H3N2 isolates were antigenically distinct from the A/Wyoming/3/03 vaccine strain.
  • Four key amino acid substitutions were identified in most isolates compared to the vaccine strain.
  • Substitutions were located in or near antibody-binding sites, including a notable K145N substitution.

Conclusions:

  • H3N2 influenza viruses continue to evolve, demonstrating antigenic drift from established vaccine strains.
  • The observed substitutions suggest ongoing viral adaptation and potential immune escape.
  • The 2005-2006 Northern Hemisphere vaccine strain was updated to A/California/7/2004 to better match circulating strains.

More Related Videos

Nasal Wipes for Influenza A Virus Detection and Isolation from Swine05:59

Nasal Wipes for Influenza A Virus Detection and Isolation from Swine

Published on: December 4, 2015

Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals09:31

Fluorescence-based Neuraminidase Inhibition Assay to Assess the Susceptibility of Influenza Viruses to The Neuraminidase Inhibitor Class of Antivirals

Published on: April 15, 2017

Related Concept Videos

Influenza01:27

Influenza

Influenza is an acute, highly communicable viral disease that affects the respiratory tract and is responsible for seasonal epidemics worldwide. Influenza A is the most prevalent type associated with widespread outbreaks and is subtyped based on two surface glycoproteins: hemagglutinin (H) and neuraminidase (N), as in H1N1. These glycoproteins are essential for viral infectivity, transmission, and immune recognition. Transmission occurs primarily through respiratory droplets and contaminated...
Inhibitors Of Virion Release01:25

Inhibitors Of Virion Release

Viral replication and dissemination rely on efficient mechanisms for host cell entry, genome replication, assembly, and release. Influenza viruses, such as types A and B, are negative-sense single-stranded RNA viruses with a segmented genome, that depend on two critical surface glycoproteins to carry out these processes: hemagglutinin (HA) and neuraminidase (NA). HA initiates infection by binding to sialic acid residues on the surface of host epithelial cells, facilitating receptor-mediated...
Poliomyelitis01:17

Poliomyelitis

Poliomyelitis is caused by poliovirus, a small, non-enveloped, positive-sense RNA virus of the Picornaviridae family and Enterovirus genus. Transmission occurs primarily via the fecal-oral route, often through ingestion of contaminated water or food. The virus initially replicates in the oropharynx and intestinal mucosa, particularly in lymphoid tissues such as the tonsils, Peyer’s patches, and regional lymph nodes. Primary viremia follows, allowing dissemination throughout the body.In most...
Arboviral Encephalitis01:25

Arboviral Encephalitis

Arboviral encephalitis refers to brain inflammation caused by arthropod-borne viruses, particularly those transmitted through mosquito vectors. Among these, West Nile virus (WNV), a member of the Flaviviridae family, is a significant public health concern. WNV is an enveloped, positive-sense, single-stranded RNA virus. Human infection typically begins when an infected mosquito introduces the virus into the dermis during feeding. The primary transmission cycle involves birds as amplifying hosts...