Background
Avian influenza A (H5N1) virus is one of the most important public health concerns worldwide. It has been detected and identified in South East Asia since 2003. In 2005, the virus was already spread to many countries in Europe, Asia and Africa [
1]. Later it interrupted international travel and negatively affected the world economy especially tourism.
In December 2005, the first case of H5N1 in Egypt was detected in a migrating bird in Damietta Governorate. In mid-February 2006, H5N1 infection was reported in Egypt among domestic poultry in more than 15 governorates, resulting in severe losses for the poultry industry. In March 2006, the first human case of H5N1 in Egypt was detected [
2]. Egypt had the highest number of confirmed human avian influenza cases outside Asia. As of 4 March 2010, 104 human cases, including 30 fatalities, had been recorded in Egypt [
3,
4].
Whey proteins have been reported to have numerous therapeutic applications including effects on bone (stimulate proliferation and differentiation of osteoblastic cells as well as suppress bone resorption and increase femoral bone strength), muscles (enhancing muscle hypertrophy and strength due to its leucine content), blood (lower blood pressure and reduce the risk of hypertension), brain (increase brain serotonin levels), immune system (stimulate immunity and improving immune function), cancer (increase NK cell function and glutathione levels), wound healing (essential for post-surgical wound healing and protein depletion delays healing time), and aging (antiaging agent due to the whey content of glutathione/antioxidant component). Furthermore, they act as antioxidant, antihypertensive, antiviral, antimicrobial, chelating agent and prevent cardiovascular diseases and osteoporosis [
5,
6]. The biological value of whey proteins has also been reviewed for their antimicrobial and antiviral functions [
7‐
11].
Modification of whey proteins to enhance or alter their biological and functional properties may increase its applications. Whey proteins modification can be accomplished by chemical, enzymatic, or physical techniques [
12]. Additional negative charges on β-lactoglobulin (BLG), α-lactalbumin (ALA) and human serum albumin (HSA) endowed them a significant antiviral activities against human immunedeficiency viruses—HIV-1 and HIV-2 [
13‐
17]. BLG modified with 3-hydroxyphthaloylacid (3HP) inhibited the infection with HIV-1, Herpes simplex virus types 1 and 2 and human cytomegalovirus [
18,
19]. In addition, many studies reported that increasing the net positive charge on whey proteins led to enhancement of its antiviral activity. Esterified whey proteins showed antiviral activity against poliovirus type-1, Coxsackie virus B6, human cytomegalovirus, Herpes simplex virus type 1 and human influenza virus A subtype H3N2 & subtype H1N1 [
20‐
24].
Therefore, it was thought worthwhile to test the efficacy of native and modified whey proteins fractions against influenza virus subtype H5N1which may be useful for the prophylaxis and treatment of influenza viruses and at the same time can be a potential and low cost alternative candidate for an anti-influenza agent.
Conclusion
From the presented data, it can be concluded that esterification of LF followed by BLG and lastly by ALA enhances its antiviral activities against H5N1 infected into MDCK cell lines which is dependent on the concentration of the tested proteins. Consequently, applying this technique is associated with a protective action on the cell lines subjected to the viral infection. Further studies are needed to improve the antiviral activity of both of α-lactalbumin and to a less extent β-lactoglobulin.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
SHT carried out the study design, participated in data organization, wrote and revised the manuscript; MAM helped in performance of the experiments; MZS carried out the study design and revised the manuscript; AIA participated in the design of the study and revised the manuscript; MMA carried out most of the experiments, participated in data organization, wrote and revised the manuscript; WHE helped in performance of the experiments.
All authors read and approved the final manuscript.