The circulation of the highly pathogenic avian influenzavirus (HPAI) H5N1 has intensified globally since 2021 with mass mortality in wild birds and poultry and incidental infections in mammals such as cattle.
The virus is a subtype of the influenza A virus belonging to the family Orthomyxoviridae which consists of viruses with a negative single-stranded RNA genome. The genome has eight segments encoding at least 11 different proteins, including hemagglutinin (HA) and neuraminidase (NA) glycoproteins. Apart from causing respiratory infections, HPAI H5N1 viruses can also affect the central nervous system (CNS) in birds and mammals.
HPAI, which may be carrier over long distances by migratory birds as well, represent a significant challenge to global public health.
Among the various of HPAI, the H5N1 virus is considered the most pathogenic. It was first reported in 1959 in Scotland from poultry and in humans in 1997 in Hong Kong. During 2003 and 2023, the World Health Organization has recorded 878 cases of HPAI H5N1 infection in humans 23 countries and mortality rate of 52%.
A biosafety level 3 (BSL-3) facility is needed to handle H5N1 virus. Inoculation of embryonated chicken eggs is the gold standard for the initial isolation of the virus. Subsequently, it can be grown in established cell lines such as the Madin-Darby canine kidney (MDCK) cells. Countries such as the U.S. consider HPAIVs among select agents, thus requiring corresponding restrictions on their transport, storage and handling.
The virus is excreted in the saliva, mucus, and feces of infected birds and human cases occur via contact with infected birds, mostly poultry. Greater awareness of such facts is crucial to protect the general public for exposure to the virus in poultry farming as well as in parks with wild birds.
While several drugs (e.g., amantadine and rimantadine) are now available to counter the virus, their effectiveness depends largely on how early the chemotherapy is initiated in the course of the infection.
As of April 2024, and according the Canadian Food Inspection Agency (CFIA), the virus has not been detected in Canadian cattle or any other livestock. However, the virus is already widespread in birds across the country with an estimated 11 million cases in farmed birds to date. In Canada, the disease is federally reportable in any species, cattle included. Currently, there are no restriction on cross-border trade in cattle.
CREM Co Labs has experience in and facilities for working with influenzaviruses (e.g., strain PR8 of Influenza A). Influenzaviruses can be cultured either in embryonated chicken eggs or cell cultures. ASTM E1053 and ASTM E2197 or their modified versions can be used for efficacy testing of different technologies against such viruses.
Further reading:
- Xie, R., Edwards, K.M., Wille, M. et al. The episodic resurgence of highly pathogenic avian influenza H5 virus. Nature 622, 810–817 (2023). https://doi.org/10.1038/s41586-023-06631-2
- Siegers JY, Ferreri L, Eggink D, Veldhuis Kroeze EJB, Te Velthuis AJW, van de Bildt M, Leijten L, van Run P, de Meulder D, Bestebroer T, Richard M, Kuiken T, Lowen AC, Herfst S, van Riel D. Evolution of highly pathogenic H5N1 influenza A virus in the central nervous system of ferrets. PLoS Pathog. 2023 Mar 10;19(3):e1011214. doi: 10.1371/journal.ppat.1011214. PMID: 36897923; PMCID: PMC10032531.
- Javad Charostad, Mohammad Rezaei Zadeh Rukerd, Shahab Mahmoudvand, Davood Bashash, Seyed Mohammad Ali Hashemi, Mohsen Nakhaie, Keivan Zandi,
- A comprehensive review of highly pathogenic avian influenza (HPAI) H5N1: An imminent threat at doorstep, Travel Medicine and Infectious Disease, Volume 55, 2023, 102638, ISSN 1477-8939, https://doi.org/10.1016/j.tmaid.2023.102638.
- Lauren Pelley · CBC News · Posted: Apr 30, 2024 4:00 AM EDT | Last Updated: April 30