S-layer proteins of Lactobacillus acidophilus inhibits JUNV infection

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• 作者：Marí ; a Guadalupe Martí ; nez¹ ; Mariano Prado Acosta¹ ; Né ; lida A. Candurra ; Sandra M. Ruzal ; ^{sandra@qb.fcen.uba.ar}
• 关键词：Surface layer ; Lactobacillus ; Antiviral
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2012
• 出版时间：15 June, 2012
• 年：2012
• 卷：422
• 期：4
• 页码：590-595
• 全文大小：979 K

文摘

It has been previously described that S-layer binds to the C-type lectin DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN, CD209). It was also shown that DC-SIGN is a cell-surface adhesion factor that enhances viral entry of several virus families. Among those, Junin virus (JUNV) entry is enhanced in cells expressing DC-SIGN and for that reason surface-layer protein (S-layer) of Lactobacillus acidophilus ATCC 4365 was evaluated as a possible JUNV inhibitor. Experiments using 3T3 cells stably expressing DC-SIGN, showed an almost complete inhibition of JUNV infection when they were treated with S-layer in a similar extend as the inhibition shown by mannan. However no inhibition effect was observed in 3T3 wild type cells or in 3T3 cells expressing liver/lymph node-specific ICAM-3 grabbing nonintegrin (L-SIGN or DC-SIGNR or CD209L).

Treatments with S-layer during different times in the infection demonstrated that inhibition was only observed when S-layer was presented in early stages of the viral infection. This inhibition does not involve the classic recognition of mannose by this C-type lectin as the S-layer showed no evidence to be glycosylated. In fact, the highly basic nature of the S-layer (pI > 9.5) seems to be involved in electrostatic interactions between DC-SIGN and S-layer, since high pH abolished the inhibitory effect on infection cause by the S-layer. In silico analysis predicts a Ca²⁺-dependant carbohydrate recognition domain in the SlpA protein.

This novel characteristic of the S-layer, a GRAS status protein, contribute to the pathogen exclusion reported for this probiotic strain and may be applied as an antiviral agent to inhibit several kinds of viruses.