Vaginal microbiota and human papillomavirus infection among young Swedish women

Abstract

Human papillomavirus (HPV) infection is one of the most common sexually transmitted diseases. To define the HPV-associated microbial community among a high vaccination coverage population, we carried out a cross-sectional study with 345 young Swedish women. The microbial composition and its association with HPV infection, including 27 HPV types, were analyzed. Microbial alpha-diversity was found significantly higher in the HPV-infected group (especially with oncogenic HPV types and multiple HPV types), compared with the HPV negative group. The vaginal microbiota among HPV-infected women was characterized by a larger number of bacterial vaginosis-associated bacteria (BVAB), Sneathia, Prevotella, and Megasphaera. In addition, the correlation analysis demonstrated that twice as many women with non-Lactobacillus-dominant vaginal microbiota were infected with oncogenic HPV types, compared with L. crispatus-dominated vaginal microbiota. The data suggest that HPV infection, especially oncogenic HPV types, is strongly associated with a non-Lactobacillus-dominant vaginal microbiota, regardless of age and vaccination status.

Fig. 1. Comparison of HPV prevalence, HPV vaccination status, and microbial diversity in the youth clinic and the cervical screening samples.

a Significantly higher HPV prevalence was observed from the youth clinic samples than the cervical screening samples. b Significantly higher HPV vaccination coverage was shown in samples from the youth clinic than samples from the cervical screening. c Microbial alpha diversity based on Shannon analysis did not show the difference between samples from the youth clinic and the cervical screening. Every dot in the violin plot represents one individual. Data were presented as mean values with standard deviations. d Principal coordinates analysis (PCoA) of microbial species data based on Bray-Curtis distance matrix demonstrated three main vaginal microbiota clusters. Statistical significance between the groups was tested by Fisher’s exact test in a and b, and by Wilcoxon rank-sum one-sided test in c (p = 0.108). ***p < 0.001 and ****p < 0.0001. HPV+: HPV-infected, HPV−: HPV-uninfected.

Fig. 2. Difference in vaginal microbiota of HPV-uninfected and HPV-infected young women.

a Vaginal microbiota at the genus/species level from HPV-uninfected young women. Except BVABs, the following criteria were used in order to show the important and abundant taxa clearly: (1) Bacteria with over 1% mean relative abundance in all the samples. (2) Lactobacillus species that have more than 10% of reads in any sample. (3) Non-Lactobacillus genera that have over 30% of reads in any sample. b Vaginal microbiota at genus/species level from HPV-infected young women. Same criteria were used as in a. c Microbial alpha diversity (Shannon) comparison between groups of HPV-uninfected and HPV-infected young women demonstrated a significantly higher vaginal microbiota diversity among HPV-infected women by Wilcoxon rank-sum one-sided test. Data were presented as mean values with standard deviations. ***p < 0.001. HPV+: HPV-infected, HPV−: HPV-uninfected.

Fig. 3. Microbial alpha diversity analysis based on Shannon index according to HPV oncogenic type, infected numbers and HPV types.

a Microbiota diversity of participant group of uninfected women, and the groups infected with oncogenic plus non-oncogenic HPVs, oncogenic HPVs, non-oncogenic HPVs and probably oncogenic HPVs were compared. The five groups showed significantly different diversity (Kruskal–Wallis test; p < 0.05). Groups with oncogenic plus non-oncogenic HPVs and oncogenic HPVs showed statistical higher diversity compared with HPV-uninfected group (Wilcoxon one-side test; *p < 0.05 and ****p < 0.0001). b Microbiota diversity comparison of HPV-uninfected group, and groups infected with single and multiple HPV types. The diversities are significantly different among the three groups (Kruskal–Wallis test; p < 0.005). Significant higher microbiota diversity of participants infected with single and multiple HPV types was observed compared with HPV-uninfected women (Wilcoxon one-side test; *p < 0.05, ***p < 0.001). c Microbiota diversity among participants infected with different HPV types in comparison with uninfected women. Significantly higher microbiota diversity was observed with women infected with HPV39, 56, and 42, compared with uninfected women. Statistical significance between the groups was tested by Wilcoxon one-side test adjusted by Benjamini–Hochberg correction. (*q < 0.05). Data was presented as mean values with standard deviations. HPV−: HPV-uninfected, O-HPV: oncogenic HPV, NO-HPV: non-oncogenic HPV, PO-HPV: probably oncogenic HPV.

Fig. 4. Bacterial species/genera presented significantly different in HPV-infected and HPV-uninfected women.

BVAB1, BVAB2, Sneathia, Prevotella, and Megasphaera were the bacterial species/genera that significantly higher presented in HPV-infected women than HPV-uninfected women. Analysis only conducted on the taxa listed in Fig. 2. Statistical significance between the groups was tested by two-sided Wilcoxon rank-sum test adjusted by Benjamini–Hochberg correction. *q < 0.05, **q < 0.01. Data was presented as median values with the interquartile and upper adjacent values indicated by the thick and thin lines, separately. HPV+: HPV-infected, HPV−: HPV-uninfected.

Fig. 5. HPV infection and microbiota diversity based on HPV vaccination status and age.

a HPV vaccination status in all the samples showed a decreased trend in vaccination coverage as age increased. b HPV prevalence and oncogenic HPV prevalence in all samples according to age. An overall high HPV prevalence was observed between age of 18–26. Most of the HPV infection contained oncogenic HPV in all the age groups. c Microbial alpha diversity based on Shannon index of all the samples showed no significant difference among age groups (Kruskal–Wallis test; p > 0.05). d Microbial alpha diversity based on Shannon index of all the samples did not show significant difference between the groups with and without vaccination (Wilcoxon rank-sum one-sided test; p > 0.05). Data were presented as mean values with standard deviations.