Hemagglutination Assay for Influenza Virus

Area of Science:

• Veterinary Virology
• Diagnostic Microbiology

Background:

• The hemagglutination assay (HA) is a widely used method for detecting hemagglutinating agents.
• These agents, such as type A influenza, are often found in cell culture supernatant or amniotic-allantoic fluid from embryonated chicken eggs.
• HA detects both live and inactivated viruses but requires amplification from clinical samples.

Purpose of the Study:

• To describe validated methods for screening and identifying hemagglutinating viruses.
• To detail the procedures used by the US National Veterinary Services Laboratories.

Main Methods:

• Utilizes the hemagglutination assay (HA) for screening.
• Involves harvesting cell culture supernatant or amniotic-allantoic fluid from embryonated chicken eggs.
• May require virus isolation for amplification prior to HA testing.

Main Results:

• The HA test can detect hemagglutinating agents, including type A influenza.
• The assay is semi-quantitative, with one hemagglutinating unit (HAU) approximating 5-6 log10 of virus.
• Factors like erythrocyte quality and user expertise can influence test interpretation.

Conclusions:

• The hemagglutination assay is a cost-effective and straightforward screening tool for hemagglutinating viruses.
• Standardized methods are crucial for consistent results in diagnostic laboratories.
• Further amplification may be necessary for sensitive detection in clinical specimens.