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Gene & Protein in Disease A One Health approach for avian influenza

spreading to all tissues through the bloodstream, and leading virus enables faster and more efficient monitoring of the
to a high mortality rate. At present, avian influenza poses a infectious disease. Moreover, understanding the molecular
significant global public health concern due to its zoonotic mechanisms employed by the etiological agent to expand
potential. Among the various viral strains, the hemagglutinin its host spectrum is of pivotal importance for the timely
5 neuraminidase 1 (H5N1) subtype demonstrates a broad adoption of control measures and the design of additional
host spectrum, extending to humans and other mammals, prevention strategies. Emphasizing the multifaceted
where it elicits severe diseases or death. 4 aspects of this disease suggests the exploration of novel
Given the above, it is imperative that new cases of research avenues aimed at tackling such a burdensome
avian influenza be promptly reported to health authorities, disease from a clinical and economic standpoints.
regardless of whether they involve HPAI or LPAI, due to their 2. Propagation of the avian virus in
capacity to mutate. While the precise mechanisms driving humans: Molecular basics of a potential
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the mutation from LPAI to HPAI remain incompletely
understood, genetic drift and genetic shift are widely pandemic
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recognized as the primary evolutionary mechanisms. A major concern regarding avian influenza lies in the virus’s
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Literature reports vary regarding the mutation rate, with capability to undergo genetic changes and reassortment
some cases indicating rapid mutation, while in others, LPAI events, which are associated with altered infectivity and
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viruses circulate for several months before undergoing adaptation to new hosts. Following these changes, the
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mutations. Clearly, the longer the circulation of LPAI, virus acquires the ability to spread from human to human,
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the greater the probability of mutation. The primary thus posing a high pandemic risk.
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transmission route for avian influenza viruses involves
direct contact between animals, although transmission can Among the mutations known to enhance the virus’s
also occur through intermediate hosts such as pigs and, capability for human-to-human transmission, especially
less frequently, domestic animals, including dogs and cats. when shed through aerosols and/or droplets, are those
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These intermediary hosts facilitate viral transmission to affecting the glycosylation sites of the H5N1 virus. These
the human sphere (Figure 1). genetic modifications primarily occur in the polymerase
basic (PB) 2 subunit of the polymerase, predominantly
Infected animals have the potential to release viral within the C-terminal domain. These genetic modifications
particles through feces, saliva, or nasal secretions into the result in amino acid exchanges, such as substitution
surrounding environment, thereby easily contaminating at position 627 from glutamic acid to lysine (E627K)
water, mud, and soil. Within these milieus, avian influenza and substitution at position 701 from aspartic acid to
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viruses can survive for varying durations, ranging from asparagine (D701N). Both mutations are also responsible
several days to months, depending on environmental for the adaptation of other avian viruses to mammalian
conditions and viral concentrations, thus perpetuating the hosts, and the E627K mutation has also been identified as a
transmission circle. 12 determinant of airborne transmission of the H5N1 virus in
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The purpose of this work is to underline the One ferrets. Furthermore, mutations of PB 1 and PB2 subunits
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Health approach to avian influenza, acknowledging its also have implications for drug resistance. For example,
various modes of transmission. Improving awareness Buthelezi et al. observed peramivir-resistant H5N1 strains
of the transmission strategies employed by the zoonotic with an H274Y-I222K double mutation. 14
The increased tropism of H5N1 toward a wider range of
animals implies difficulties in controlling the disease, as it
consequently increases the number of virus reservoirs. These
factors favor the spillover phenomenon and increase the
probability of transmission to humans, potentially resulting
in an outbreak or even a pandemic. Finally, it could impact
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ecosystem dynamics by affecting various animal populations
and their ecological contributions to viral transmission. 16
3. Diagnosis of Avian Influenza: Pros and
Cons
At present, the main methods commonly used for avian
influenza virus detection include hemagglutination
Figure 1. Transmission routes of the avian influenza virus. assay (HA), hemagglutination inhibition assay, reverse

Volume 3 Issue 1 (2024) 2 https://doi.org/10.36922/gpd.2327