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. 2024 Feb 20;25(5):2492.
doi: 10.3390/ijms25052492.

Vaginal Lactobacilli Supernatants Protect from Herpes Simplex Virus Type 1 Infection in Cell Culture Models

Elisa Avitabile  1 , Laura Menotti  1 , Barbara Giordani  1 , Vanessa Croatti  1 , Carola Parolin  1 , Beatrice Vitali  1
Affiliations

Vaginal Lactobacilli Supernatants Protect from Herpes Simplex Virus Type 1 Infection in Cell Culture Models

Elisa Avitabile et al. Int J Mol Sci. .

Abstract

A healthy vaginal microbiota hosts Lactobacillus as the most predominant genus. Lactobacilli play a role in human health through the production of diverse antimicrobial substances that can act against human pathogens or modulate the immune system. Previous reports highlighted the ability of vaginal lactobacilli to counteract viruses causing STIs, e.g., HIV-1 and HSV-2. In this report, we analyze the activity of supernatants of vaginal lactobacilli against HSV-1 infection, which is becoming increasingly relevant as a STI. We show that the supernatants of two vaginal Lactobacillus species (i.e., L. crispatus and L. gasseri) were active at neutralizing HSV-1 infection in two different cell lines of human and simian origin. Specifically, we demonstrate that L. crispatus strains are the most effective in antiviral activity, as evidenced by the comparison with a vaginal pathogen taken as reference. The effect was specific and not attributable to the generic toxicity of the supernatants to the cells. Our results pave the way for the development of probiotics to limit the impact of HSV-1 infection on women's health.

Keywords: HeLa cells; Vero cells; cultural supernatants; herpes simplex virus type 1; vaginal lactobacilli; virus growth inhibition.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Antiviral activity of CFSs from L. crispatus BC3 and BC5, L. gasseri BC12 and BC13, E. faecalis BC101, and MRS medium on HeLa cells. HSV-1 was mock pretreated or pretreated with CFSs or MRS medium at different dilutions (1:2, 1:4, and 1:8), and virus yield was determined at (a) 24 h and (b) 48 h post-infection. Results are expressed as log PFU/mL (mean ± SD, n = 3). * p < 0.05 (vs. mock).
Figure 2
Figure 2
Antiviral activity of CFSs from L. crispatus BC3 and BC5, L. gasseri BC12 and BC13, E. faecalis BC101, and MRS medium on Vero cells. HSV-1 was mock pretreated or pretreated with CFSs or MRS medium at different dilutions (1:2, 1:4, and 1:8), and virus yield was determined at (a) 24 h and (b) 48 h post-infection. Results are expressed as log PFU/mL (mean ± SD, n = 3). * p < 0.05 (vs. mock).
Figure 3
Figure 3
Effect of CFSs on HeLa cell viability at 24 h and 48 h after exposure. CFSs from L. crispatus BC3 and BC5, L. gasseri BC12 and BC13, E. faecalis BC101, and MRS medium were tested at the highest concentration used in the antiviral assay (corresponding to a 1:2 dilution) by means of (a) the MTT assay and (b) the erythrosine B exclusion test. Results are expressed as % of mock (100%) (mean ± SD, n = 3).
Figure 4
Figure 4
Effect of CFSs on Vero cell viability at 24 h and 48 h after exposure. CFSs from L. crispatus BC3 and BC5, L. gasseri BC12 and BC13, E. faecalis BC101, and MRS medium were tested at the highest concentration used in the antiviral assay (corresponding to a 1:2 dilution) by means of (a) the MTT assay and (b) the erythrosine B exclusion test. Results are expressed as % of mock (100%) (mean ± SD, n = 3).
Figure 5
Figure 5
Summary of antiviral activity exerted by CFSs from L. crispatus BC3 and BC5, L. gasseri BC12 and BC13, E. faecalis BC101, and MRS medium at three dilutions (1:2, 1:4, and 1:8) on HeLa and Vero cells. Different shaped symbols were used for the bacterial strains and controls. Significances vs. MRS medium and CFS-BC101 are indicated (* p < 0.0332, ** p < 0.0021, *** p < 0.0002, **** p < 0.0001, ns: not significant).
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