Mitochondrial diversity and phylogeographic analysis of Pediculus humanus reveals a new Amazonian clade “F”

Pediculus humanus is an obligate and highly intimate bloodsucking insect parasite of humans that has two ecotypes, head louse and body louse. This study analyzed genetic diversity at three mitochondrial genes (cytochrome b [cytb], cytochrome oxidase subunit 1 [cox1] and 12S ribosomal RNA [12S]) in 98 head lice collected from an isolated Native American population from the Wayampi community in Trois-Sauts, French Guiana. These results are integrated with all prior data of P. humanus (1402 cytb, 743 cox1 and 344 12S) from other parts of the world. The phylogenetic analysis revealed six highly divergent and well-supported monophyletic clades. Five clades corresponded to the previously recognized mitochondrial clades A, D, B, C and E, while the sixth (clade F) was novel, as it exhibited 5.4%, 3.7% and 3.6% divergence at cytb, cox1 and 12S, respectively, from its nearest neighbor clade B. Interestingly, the clade F has only been recovered in a few lice sequences from Mexico and Argentina, while it was the most common lineage in the Amazonian lice, which hints its association with the Native American region. Furthermore, Pediculus mjobergi, a New World monkeys' louse, which is thought to be transmitted to monkeys from the first humans that had reached the American continent thousands of years ago, also belonged to this clade, suggesting that this louse may not be a separate species but an evolutionary lineage of P. humanus. The discovery of new Amazonian clade F with the recovery of additional haplotypes within each of the five clades demonstrates that the levels of genetic diversity in P. humanus are higher than previously thought.

Supplementary data to this article can be found online at https://doi.org/10.1016/j.meegid.2019.02.006

Figure  S1. (A)  Cytb  sequences  alignment  and  (B)  DNA  sequence  chromatograms  of clade F haplotypes identified in this study showing the polymorphic sites.

Figure  S2.  (A)  Cox1  sequences  alignment  and  (B)  DNA  sequence  chromatograms  of clade F haplotypes identified in this study showing the polymorphic sites. 

Figure S2.(A) 12S sequences alignment and (B) DNA sequence chromatograms of clade F haplotypes identified in this study showing the polymorphic sites.

Figure  S4.  (A)  12S  sequences  alignment  of  clade  F  haplotypes  and  (B)  12S  DNA sequence chromatogram of P. mjobergi amplified in this study.

Figure  S5.Maximum-likelihood  (ML)  analysis  of Cytb  (A), Cox1  (B)  and  12S  (C) haplotypes of Pediculushumanus. Bootstrap values (500 replicates) are shown above thebranches.  The  scale  bar  shows  K2P  distances.  The  node  for  each  clade  with  multiple haplotypes is collapsed to a vertical triangle, with the horizontal depth indicating the level of intra-clade divergence. Bracketed numbers next to each clade’s name indicate the number of haplotypes  analyzed  and  the  average  intra-clade  distance.  Analyses  were  conducted  in MEGA6.

Table  S1.  Additional  louse  specimens  included  in  this  study,  obtained  from  the  private  frozen collection of world lice belonging to our laboratory.

Table  S2.Pediculus  mjobergi  sequences  from  new  world  monkey  (Alouatta  caraya) included in this study. The cox1 and cytb P. mjobergi sequences analyzed in this study were those  reported  by  Drali  et  al.  (2016)  collected  from  two  monkey  individuals  B2188  and B1395.  The  12S  sequences  were  amplified  in  this  study  from  three P.  mjobergi  specimens from monkey individual B2188.

Table S3. Geographic occurrences and frequencies of cytb haplotypes of human head and body lice.

Table  S4.  Geographic  occurrences  and  frequencies  ofcox1  haplotypes  of  human  head and body lice

Table S5. Geographic occurrences and frequencies of 12S haplotypes of human head 576 and body lice.

Table  S6.  Distribution of  the  head  lice  haplotypes identified  in  this  study,  according  to mitochondrial genes, among the 22 infested Amazonian individuals.