Charge modification of plasma and milk proteins results in antiviral active compounds

Abstract

Previous studies have shown that acylated plasma and milk proteins with increased negative charge, derived from various animal and human sources, are potent anti-HIV compounds. The antiviral effects seemed to correlate positively with the number of negative charges introduced into the various polypeptides: proteins with a high content of basic amino acids in which all of the available epsilonNH2 groups were anionized yielded the most potent anti-HIV compounds. It remained unclear however whether the total net negative charge of the various derivatized proteins, or rather the charge density on the protein backbone, is essential for the observed anti-HIV activity. Earlier studies have shown that acylated albumins preferentially block the process of HIV/cell fusion through binding to the HIV envelope proteins gp120 and gp41 as well as to the cell surface of the HIV target cells. Some of these polyanionic proteins have been shown to interfere also with the gp120-CD4 mediated virus/cell binding. The relative contribution of these effects to the anti-HIV activity may depend both on the total negative charge introduced as well as the hydrophobicity of the acylating reagent added to the particular proteins. In this study we show that the higher the charge density of the derivatized proteins, the more potent their HIV replication inhibiting effects are. In contrast, the addition of positive charge to the studied plasma and milk proteins through amination resulted in a reduced anti-HIV activity but a clearly increased anti-HCMV activity, with IC50 values in the low micromolar concentration range. Interestingly, native lactoferrin (Lf) was antivirally active against both HIV and HCMV. Acylation or amination of Lf increased the anti-HIV and anti-HCMV activity, respectively. The N-terminal portion of Lf appeared essential for its anti-HCMV effect: N-terminal deletion variants of human Lf were less active against HCMV. Circular dichroism of the modified proteins showed that the secondary structure of the tested proteins was only moderately influenced by acylation and/or covalent attachment of drugs, making these (derivatized) proteins useful candidates as antiviral agents and/or intrinsically active drug carriers. The relatively simple chemical derivatization as well as the abundant sources of blood plasma and milk proteins provides attractive opportunities for the preparation of potent and relatively cheap antiviral agents for systemic or local applications.

Enhanced Antiviral Activity of Soybean β‐Conglycinin‐Derived Peptides by Acylation with Saturated Fatty Acids

“…According to Pan and others (2007), acylation of lactoferrin abolishes anti‐HCMV and FCV inhibitory activity, also reduces antiviral activity against PV though effective against influenza virus. Results of this study agree with Swart and others (1999), who observed that acylation increased the antiviral activity due to charge modification of proteins. The present study clearly indicates that acylated 7S‐peptides inhibited FCV activity.…”

“…Higher modification degree practically reduces positively charged groups causing highly modified proteins to be more negatively charged. Several other proteins had an enhanced antiviral effect with the increased introduction of negative charges (Swart and others 1996, 1999). Enzymatic hydrolysis alters structure, charge balance, and hydrophobicity of protein to modify functionalities whereas acylation increased negative charge density of soy peptides through covalent attachment of fatty acyl residues.…”

“…Enzymatic hydrolysis alters structure, charge balance, and hydrophobicity of protein to modify functionalities whereas acylation increased negative charge density of soy peptides through covalent attachment of fatty acyl residues. Charge modification of plasma and milk proteins resulted in active antiviral compounds (Swart and others 1999). According to Pan and others (2007), acylation of lactoferrin abolishes anti‐HCMV and FCV inhibitory activity, also reduces antiviral activity against PV though effective against influenza virus.…”

2’-Fucosyllactose Inhibits Coxsackievirus Class A Type 9 Infection by Blocking Virus Attachment and Internalisation

“…Several ingredients derived from breast milk possess antiviral activities. LF inhibits various viruses, including enveloped viruses such as SARS-CoV-2 [ 26 , 27 ], human hepatitis C virus [ 28 ], human hepatitis B virus [ 29 ], HIV [ 30 ], herpes viruses [ 31 ], hantaviruses [ 32 ], and non-enveloped viruses such as human papillomavirus (HPV) [ 9 ], enterovirus 71 (EV71) [ 13 ], echovirus 6 [ 33 ], adenovirus [ 34 ], and feline virus [ 35 ]. Whey protein is a mixture of α-whey protein, immunoglobulins, serum albumin, LF, and lysozyme.…”

RETRACTED ARTICLE: Inhibition of Tomato Yellow Leaf Curl Virus (TYLCV) using whey proteins

“…The charge on the antiviral protein plays an indispensable role in this interaction. Chemical modifications lead to changes in the charges on milk proteins which can enhance their antiviral properties [41,42]. …”