At the crossroads of vaginal health and disease, the genome sequence of Lactobacillus iners AB-1

Abstract

Lactobacilli have long been regarded as important constituents of the healthy human vagina. Lactobacillus iners is the most frequently detected bacterial species in the vagina, but little is known about its characteristics. We report a description of the whole-genome sequence of L. iners AB-1 along with comparative analysis of published genomes of closely related strains of lactobacilli. The genome is the smallest Lactobacillus reported to date, with a 1.3-Mbp single chromosome. The genome seems to have undergone one or more rapid evolution events that resulted in large-scale gene loss and horizontal acquisition of a number of genes for survival in the vagina. L. iners may exhibit specialized adaptation mechanisms to the vaginal environment, such as an iron–sulfur cluster assembly system, and several unique σ factors to regulate gene transcription in this fluctuating environment. A potentially highly expressed homolog of a cholesterol-binding lysin may also contribute to host cell adhesion or act as a defense mechanism against other microbes. Notably, there is a lack of apparent adhesion proteins, but several cell-anchor proteins were identified and may be important for interaction with the host mucosal tissues. L. iners is widely present in healthy females as well as those suffering from bacterial vaginosis or who have undergone antimicrobial therapy, suggesting that it is an important indigenous species of the vagina.

Lactobacillus-dominated cervicovaginal microbiota associated with reduced HIV/STI prevalence and genital HIV viral load in African women

“…Recent genomic and transcriptomic studies suggest that L. iners is highly adapted to the vaginal compartment (Macklaim et al, 2011). However, it differentially expresses over 10% of its genome in dysbiotic compared with healthy states, with increased expression of a cytolysin, mucin, glycerol transport and related metabolic enzymes (Macklaim et al, 2013).…”

Effect of iron on the probiotic properties of the vaginal isolate Lactobacillus jensenii CECT 4306

“…This rich vaginal environment is protected against the invasion of undesirable microorganisms by some species of Lactobacillus, such as L. crispatus, L. iners and L. jensenii; these species are so well adapted to the vaginal environment that they are seldom found outside the vagina (Macklaim et al, 2011).…”

Current views on vaginal microbiota and its impact on pregnancy outcomes

“…[14]. Дальнейшие исследования показали, что данный вид часто встречается при БВ, обнаруживается у женщин с антенатальными потерями плода в анамнезе [15,16]. Однако L. iners нередко встречается в качестве доминирующего вида и при нор-моценозе [17], но, в отличие от других видов лактобацилл, L. iners не препятствует раз-множению условно-патогенной микрофлоры.…”

“…Это при-водит к размножению анаэробов, ассоцииро-ванных с БВ. Таким образом, преобладание L. iners часто наблюдается в переходный этап между нормальным состоянием влагалищного микробиоценоза и нарушенным и может пред-располагать к развитию патогенной влагалищ-ной микрофлоры, что, в свою очередь, может быть потенциально связано с невынашивани-ем беременности и преждевременными родами [15,16,20].…”