Shedders’ bacterial microbiomes are less stable over time than non-shedders’ microbiomes.
To investigate the roles of both the microbiome and virome in discordant HIV shedding, we analyzed 125 cervicovaginal specimens collected longitudinally from 31 WLHIV in Lima, Peru (Table 1, Fig. 1A, Supplementary Table 1). Specimens were collected quarterly from participants over a period of two years as part of a larger study characterizing discordant shedding in people living with HIV4. In this study, we analyzed an average of 4 specimens per participant. Most specimens (n = 120) were cervicovaginal lavages (CVL). When CVL samples were not available, vaginal swabs (n = 2), cytobrushes (n = 2), or TearFlo paper strips (n = 1) were used to sample the cervicovaginal environment. Nine women experienced discordant HIV shedding during the study period (shedders) and 22 did not (non-shedders). Non-shedders were older than shedders at study enrollment (non-shedder median age = 34 years, shedder median age = 28 years; Mann-Whitney test, p = 0.047) (Extended Data Fig. 1A). Shedders and non-shedders had similar CD4 counts at enrollment and similar CD4 recoveries when values from enrollment and after 2 years of ART were compared (Mann-Whitney test; p = 0.94 at enrollment, p = 0.94 at final visit, p = 0.94 for change from enrollment to final visit) (Extended Data Fig. 1B). Using metagenomic next-generation sequencing (NGS) after physically enriching for bacteria, we obtained a median of 15.6x106 (IQR 13.7x106 – 17.8x106) raw read pairs and 1.95x106 (IQR 8.7x105 – 4.7x106) quality-filtered, deduplicated individual reads per sample. Most samples clustered into groups dominated by Lactobacillus crispatus (n = 29), Lactobacillus iners (n = 21), Gardnerella vaginalis (n = 48), or a mixed community (n = 21), with a few samples dominated by Lactobacillus jensenii (n = 2) or Escherichia coli (n = 4) (Fig. 1B). There were no significant differences in bacterial alpha diversity, beta diversity, or cluster assignment between different sample types (CVL, vaginal swabs, cytobrushes or TearFlo strips) (Extended Data Fig. 1C-1F, Supplementary Table 2).
Table 1
| Shedders | Non-shedders | Statistical significance |
Number of participants | 9 | 22 | N/A |
Number of specimens analyzed per participant: median (interquartile range) | 4 (4–4) | 4 (4–4) | p = 0.52 |
Age at enrollment: median (interquartile range) | 28 (24–30) | 34 (30–39) | p = 0.047 |
CD4 at enrollment: median (interquartile range) | 132 (89–223) | 141 (51.25–205.5) | p = 0.94 |
CD4 after 2 years of ART: median (interquartile range) | 454 (307.5–510) | 356.5 (295.5–415.5) | p = 0.94 |
CD4 change from initial to final visit: median (interquartile range) | 209.5 (140.25–304.5) | 208 (152–329.75) | p = 0.94 |
Statistical significance was assessed by the Mann-Whitney test, with the Benjamini-Hochberg method used to correct for multiple comparisons where appropriate. Number of specimens, age, and CD4 counts are expressed as median and interquartile range. |
Intrapersonal microbiome variation (beta diversity) was lower than interpersonal variation, suggesting intraindividual stability over time (Fig. 2A; Bray-Curtis dissimilarity; Mann-Whitney test, p = 1.9x10− 19 for non-shedders, p = 0.0019 for shedders). Shedders had higher intrapersonal microbiome beta diversity than non-shedders (Fig. 2A; Bray-Curtis dissimilarity, Mann-Whitney test, p = 0.0019). We tested the hypothesis that perturbation was most pronounced during discordant shedding by comparing diversity between discordant and non-discordant timepoints within individuals (Fig. 2B). Beta diversity was significantly higher between samples when one timepoint was discordant and the other was non-discordant, compared to pairs of non-discordant timepoints (Bray-Curtis dissimilarity; Mann-Whitney test, p = 0.014), suggesting that higher intrapersonal variation in shedders reflects dysbiosis during discordant shedding rather than prolonged fluctuations. Principal coordinates analysis (PCoA) using Bray-Curtis dissimilarity showed no association between microbiome composition and ART duration (PERMANOVA, p = 0.33) or shedder/non-shedder status (PERMANOVA, p = 0.34) (Fig. 2C), although discriminant analysis with MaAsLin250 showed higher Mycoplasma hominis relative abundance in shedders compared to non-shedders (Fig. 2D, q = 0.048). PCoA of shedder samples showed no difference between discordant and non-discordant timepoints (Fig. 2E; PERMANOVA, p = 0.85). Microbiome community clusters were not associated with shedder/non-shedder status, ART duration, or discordant shedding timepoints (Fig. 1B, Supplementary Table 2). These results suggest that no specific microbiome composition is associated with shedder/non-shedder status, ART duration, or discordant shedding events, implying that higher variation during discordant shedding reflects individual-specific, not shared, dysbioses. To determine whether this could be explained by common functional characteristics encoded by bacterial genomes that might not be reflected in taxonomic profiles, we performed functional profiling with HUMAnN351 (Extended Data Fig. 2A). We observed similar results for bacterial metabolic pathway and gene family beta diversity as for taxonomic beta diversity (Extended Data Fig. 2B-2I). 172 metabolic pathways were associated with microbiome community clusters but not with shedder/non-shedder status, discordant shedding events, or ART duration (MaAsLin2, Supplementary Table 3). Results were similar for gene families (Supplementary Table 4). This suggests that functional profiles mirror taxonomic profiles, with similar beta diversity dynamics during discordant HIV shedding.
Non-shedders’ viromes are less stable than shedders’ viromes, with anellovirus and papillomavirus relative abundance changing over time.
Given the temporal dynamics of the bacterial microbiome, we examined the virome for similar patterns. After enrichment for virus-like particles (VLPs), we visualized VLPs in specimens using epifluorescence microscopy to corroborate VLP enrichment (Extended Data Fig. 3A). VLP concentrations ranged from 2.5x105 – 2.2x108 particles per mL of VLP-enriched supernatant, with a median of 1.1x107 particles per mL (Extended Data Fig. 3B). Using metagenomic NGS of nucleic acids extracted from VLP-enriched supernatants and amplified by multiple displacement amplification (MDA), we obtained a median of 1.6x107 (IQR 4.5x106 – 2.2x107) raw read pairs and 2.4x106 (IQR 1.1x106 – 3.5x106) quality-filtered, deduplicated individual reads per sample. 12,574 unique contigs > = 500 nt were assembled from the samples and sequencing controls, and 1,596 were identified as viral. After mapping quality-filtered reads to the viral contigs, 116 samples had > 1,000 viral reads and were retained for further analysis. Samples clustered into groups dominated by Anelloviridae (n = 46), Papillomaviridae (n = 54), or bacteriophages including Microviridae and Caudoviricetes (n = 16) (Fig. 3A). Virome alpha diversity was inversely associated with ART duration (linear mixed modeling (LME), p = 7.7x10− 10 for viral contig richness, p = 8.3x10− 8 for Shannon index), with no significant difference between shedders and non-shedders (LME, p = 0.19 for richness, p = 0.90 for Shannon index) (Fig. 3B). Because MDA only amplifies DNA, we performed sequence-independent amplification (SIA) on the viral nucleic acids to amplify RNA and DNA. We found plant-infecting RNA viruses in a few samples, but no RNA viruses known to infect humans or bacteria, and most samples had no RNA viruses identified (Extended Data Fig. 4A). Therefore, we focused our analyses on the DNA virome using the MDA data.
Like bacterial microbiome variation, intrapersonal virome variation (beta diversity) was significantly lower than interpersonal variation (Fig. 3C, Bray-Curtis dissimilarity (weighted); Mann-Whitney, p = 1.4x10− 36 for non-shedders, p = 1.2x10− 12 for shedders; Fig. 3D, Sorensen dissimilarity (unweighted); Mann-Whitney, p = 2.2x10− 13 for non-shedders, p = 9.3x10− 5 for shedders). However, weighted intrapersonal variation was not significantly different between shedders and non-shedders (Fig. 3C, Bray-Curtis dissimilarity; Mann-Whitney, p = 0.71). Further, unweighted intrapersonal variation was significantly higher in non-shedders than in shedders (Sorensen dissimilarity; Mann-Whitney test, p = 0.0020) (Fig. 3D). In weighted (Bray-Curtis) PCoA, virome composition was associated with ART duration (PERMANOVA, p = 0.001) and shedder/non-shedder status (PERMANOVA, p = 0.016) (Fig. 3E). Because ART duration trended toward interaction with shedder/non-shedder status (PERMANOVA, p = 0.069), we carried out PCoA on shedders and non-shedders separately (Extended Data Fig. 5A). Virome composition was associated with ART duration in non-shedders (PERMANOVA, p = 0.001), and trended toward association with ART duration in shedders but was not significant (PERMANOVA, p = 0.072). In unweighted (Sorensen) PCoA of combined shedders and non-shedders, virus presence-absence was associated with ART duration (PERMANOVA, p = 0.001) but not shedder/non-shedder status (PERMANOVA, p = 0.63), with no interaction between ART duration and shedder/non-shedder status (PERMANOVA, p = 0.15) (Extended Data Fig. 5B). These results suggest that virome composition changes over time in WLHIV taking ART, with more pronounced changes among non-shedders.
We used differential abundance analysis (MaAsLin250) to identify viruses responsible for changes in virome beta diversity over time. Anelloviridae relative abundance was inversely associated with ART duration (q = 8.8x10− 5), while Papillomaviridae relative abundance increased over time (q = 0.037) (Fig. 4F). ART duration trended toward interaction with shedder/non-shedder status for several viral families, but these trends were not significant (Supplementary Table 5). When non-shedders were analyzed separately, Anelloviridae relative abundance decreased over time after ART initiation and Papillomaviridae relative abundance increased (Extended Data Fig. 5C). No taxa changed significantly over time in shedders. These results suggest that changes in virome composition after ART initiation are driven by Anelloviridae and Papillomaviridae, especially among non-shedders.
Anellovirus communities change over time, with decreased alphatorquevirus abundance and increased betatorquevirus proportions.
Because the Anelloviridae family contributed significantly to the temporal virome signature (Fig. 3), we performed phylogenetic analysis of the anellovirus contig ORF1 gene sequences to better define anellovirus community dynamics. We obtained predicted ORF1 sequences from 751/799 anellovirus contigs. 21 contigs had more than one predicted ORF1 sequence, for a total of 774 sequences. At the genus level, most anelloviruses were classified as alphatorqueviruses (n = 339), betatorqueviruses (n = 339), or gammatorqueviruses (n = 85), with a few hetorqueviruses (n = 4) and sequences falling outside known anellovirus genera (n = 7) (Fig. 4A). Compared to all viral genera, relative abundance of alphatorqueviruses and incomplete anellovirus genomes (i.e., without ORF1) decreased over time after ART initiation (MaAsLin2, q = 0.0019 and q = 0.0019) (Extended Data Fig. 6A). There were no significant changes in the relative abundance of other anellovirus genera. This suggests that decreased Anelloviridae relative abundance reflects decreased Alphatorquevirus relative abundance.
We used the anellovirus phylogeny to calculate UniFrac distance, a beta diversity metric that accounts for phylogenetic distance. In shedders, intrapersonal anellovirus beta diversity was significantly lower than interpersonal diversity (weighted UniFrac, Mann-Whitney, p = 2.7x10− 4), while for non-shedders there was no significant difference between intrapersonal and interpersonal anellovirus beta diversity (weighted UniFrac, Mann-Whitney, p = 0.33) (Fig. 4B). Intrapersonal variation was also significantly lower in shedders than non-shedders (Fig. 4B; Mann-Whitney, p = 3.5x10− 5). Results were similar for unweighted UniFrac distance (Extended Data Fig. 6B). These results suggest that anellovirus communities are less stable over time in non-shedders compared to shedders. In PCoA using weighted anellovirus UniFrac distance, anellovirus community compositions changed significantly by ART duration (PERMANOVA, p = 0.005), with no significant difference between shedders and non-shedders (PERMANOVA, p = 0.81) (Fig. 4C). Because ART duration trended toward interaction with shedder/non-shedder status (PERMANOVA, p = 0.078), we carried out separate PCoA analyses on non-shedder and shedder samples. In these separate analyses, ART duration was associated with anellovirus community structure in non-shedders (PERMANOVA, p = 0.006), but not in shedders (PERMANOVA, p = 0.12) (Extended Data Fig. 6C). In unweighted anellovirus UniFrac PCoA of combined shedders and non-shedders, anellovirus presence-absence was associated with ART duration (PERMANOVA, p = 0.001) but not with shedder/non-shedder status (PERMANOVA, p = 0.59), with no interaction between ART duration and shedder/non-shedder status (PERMANOVA, p = 0.31) (Extended Data Fig. 6D). We performed differential abundance analyses (MaAsLin2) to identify specific anelloviruses responsible for changing anellovirus diversity over time. When shedders and non-shedders were analyzed together, Betatorquevirus relative abundance increased and relative abundance of partial anellovirus genomes decreased relative to other anellovirus genera (Extended Data Fig. 6E; MaAsLin2, q = 0.036 and q = 0.036). When non-shedders were considered separately, Betatorquevirus relative abundance increased (MaAsLin2, q = 0.028) (Extended Fig. 6F) and Alphatorquevirus relative abundance tended to decrease but did not reach significance (MaAsLin2, q = 0.060). No anellovirus genera changed significantly over time in shedders. Together with the whole-virome analyses, where Alphatorquevirus relative abundance decreased over time in the virome as a whole, these results suggest that betatorqueviruses consequently make up a larger proportion of the remaining anellovirus community, and these changes are more pronounced among non-shedders.
We corroborated the NGS data with quantitative PCR (qPCR) specific to the untranslated region of the alphatorquevirus genome (Extended Data Fig. 7Α). Alphatorquevirus genome copy numbers were correlated with Alphatorquevirus NGS relative abundance (linear regression, p = 0.041) and trended toward association with Anelloviridae relative abundance (linear regression, p = 0.085), but not Betatorquevirus or Gammatorquevirus relative abundance (linear regression, p = 0.96 and p = 0.84, respectively) (Extended Data Fig. 7Β). Alphatorquevirus copy numbers tended toward inverse association with ART duration, but this was not significant (LME, p = 0.090) (Extended Data Fig. 7C), and there was no significant difference between shedders and non-shedders (LME, p = 0.51).
Because anellovirus abundance has previously been associated with immune status44,52–59, we considered whether increasing CD4 counts could explain decreasing anellovirus relative abundance. CD4 counts were inversely associated with Anelloviridae relative abundance (LME, p = 1.1x10− 4) (Fig. 4D), Alphatorquevirus relative abundance (Extended Data Fig. 7D, LME, p = 1.7x10− 4) and alphatorquevirus qPCR copy numbers (Fig. 4E; LME, p = 0.04). There was no association between CD4 counts and Betatorquevirus or Gammatorquevirus relative abundance (LME, p = 0.77 and p = 0.36, respectively) (Extended Data Fig. 7D). When we analyzed non-shedders separately, Anelloviridae NGS relative abundance, Alphatorquevirus NGS relative abundance and alphatorquevirus qPCR copy numbers were inversely associated with CD4 counts (LME; p = 2.1x10− 4, p = 1.3x10− 4, and p = 0.04, respectively), but there were no significant associations in shedders (Extended Data Fig. 7E). These results suggest a relationship between immune status and anellovirus abundance, specifically alphatorqueviruses, in the FGT.
Papillomavirus populations are stable over time in shedders and non-shedders.
Because the Papillomaviridae family also contributed to the temporal virome signature (Fig. 3), we conducted phylogenetic analysis of the concatenated papillomavirus contig E1, E2, L2, and L1 genes to characterize papillomavirus diversity over time. We obtained E1-E2-L2-L1 sequences from 169/190 papillomavirus contigs. Most were alphapapillomaviruses (n = 128), with some betapapillomaviruses (n = 7) and gammapapillomaviruses (n = 34) (Fig. 5A). Alphapapillomavirus relative abundance increased over time (Extended Data Fig. 8A, MaAsLin2, q = 0.044), while other papillomavirus genera did not change significantly.
Unlike anellovirus beta diversity, both non-shedders and shedders had lower intrapersonal papillomavirus beta diversity compared to interpersonal diversity, with no significant difference between shedders and non-shedders (Fig. 5B; weighted papillomavirus UniFrac distance, Mann-Whitney, p = 8.8x10− 9, p = 0.0083, and p = 0.95, respectively). Unweighted papillomavirus beta diversity results were similar (Extended Data Fig. 8B). In PCoA using papillomavirus UniFrac distance, there were no significant differences by ART duration or shedder/non-shedder status (Fig. 5C, Extended Data Fig. 8C; PERMANOVA; weighted, p = 0.33 and p = 0.28, respectively; unweighted, p = 0.18 and p = 0.10, respectively). These results suggest that papillomavirus diversity is stable over time in shedders and non-shedders.