Early-Life Colonization by Anelloviruses in Infants

Abstract

Anelloviruses (AVs) are found in the vast majority of the human population and are most probably part of a healthy virome. These viruses infect humans in the early stage of life, however, the characteristics of the first colonizing AVs are still unknown. We screened a collection of 107 blood samples from children between 0.4 and 64.8 months of age for the presence of three AV genera: the Alpha-, Beta- and Gammatorquevirus. The youngest child that was positive for AV was 1.2 months old, and a peak in prevalence (100% of samples positive) was reached between the twelfth and eighteenth months of life. Intriguingly, the beta- and gammatorqueviruses were detected most at the early stage of life (up to 12 months), whereas alphatorqueviruses, the most common AVs in adults, increased in prevalence in children older than 12 months. To determine whether that order of colonization may be related to oral transmission and unequal presence of AV genera in breast milk, we examined 63 breast milk samples. Thirty-two percent of the breast milk samples were positive in a qPCR detecting beta- and gammatorqueviruses, while alphatorqueviruses were detected in 10% of the samples, and this difference was significant (p = 0.00654). In conclusion, we show that beta- and gammatorqueviruses colonize humans in the first months of life and that breastfeeding could play a role in AV transmission.

Transmission of anelloviruses to HIV-1 infected children

“…Children born naturally tend to have higher loads of AVs compared to the ones born via the caesarian section (McCann et al, 2018). Moreover, AV DNA has been detected in breastmilk (Ohto et al, 2002;Maqsood et al, 2021), and we described recently that beta-and gammatorqueviruses are dominating both in breastmilk and in the blood of children younger than 6 months, which suggests a role of breastfeeding in AV transmission (Kaczorowska et al, 2022a). However, other means of mother-to-child transmission, such as fecal-oral or respiratory, are yet to be explored.…”

“…The healthy human virome is regarded as highly dynamic in the first months of life, both in the gut and in blood (Lim et al, 2015;Tyschik et al, 2017;Bushman and Liang, 2021;Kaczorowska et al, 2022a). The AVs colonize infants within the first 6 months of life (Lim et al, 2015;Kaczorowska et al, 2022a), yet the main source or route of the first infection is still unknown.…”

“…The healthy human virome is regarded as highly dynamic in the first months of life, both in the gut and in blood (Lim et al, 2015;Tyschik et al, 2017;Bushman and Liang, 2021;Kaczorowska et al, 2022a). The AVs colonize infants within the first 6 months of life (Lim et al, 2015;Kaczorowska et al, 2022a), yet the main source or route of the first infection is still unknown. All children in our study were born via caesarian section, were not breastfed, and still were infected by AVs in the very first months of life-thus the transmission must have occurred via a different route.…”

“…The first qPCR detected the genus alphatorquevirus, the second one detected betatorquevirus, and the third-beta-and gammatorquevirus. The qPCRs were performed as described previously (Kaczorowska et al, 2022a). Briefly, the qPCR reaction mixture consisted of 2.5 µL isolated nucleic acids (non-rolling circle amplified), 6.25 µL 2× Qiagen RotorGene Probe Master-mix (Qiagen, catalog number 204574), 0.25 µL probe, 0.5 µL forward, and 0.5 µL reverse primer (all 10 µM) and 2.5 µL H 2 O.…”

“…Children are born AV-negative (Lim et al, 2015;Liang and Bushman, 2021), and there was so far no convincing evidence of vertical transmission of AVs 10.3389/fmicb.2022.951040 (Tyschik et al, 2017). AV DNA was detected in children's blood (Tyschik et al, 2017(Tyschik et al, , 2018Kaczorowska et al, 2022a) and feces (Lim et al, 2015) in the first months of life, thus it is likely that AVs are transmitted from the mother to child during the delivery or the post-partum period. Children born naturally tend to have higher loads of AVs compared to the ones born via the caesarian section (McCann et al, 2018).…”