Molecular Characterization and Genetic Diversity of Haplogroup E Human Lice in Guinea, West Africa

Abstract

Pediculus humanus capitis, the head louse, is an obligate blood-sucking ectoparasite that occurs in six divergent mitochondrial clades (A, D, B, F, C and E). Several studies reported the presence of different pathogenic agents in head lice specimens collected worldwide. These findings suggest that head louse could be a dangerous vector and a serious public health problem. Herein, we aimed to study the mitochondrial genetic diversity, the PHUM540560 gene polymorphisms profile of head lice collected in Guinea, as well as to screen for their associated pathogens. In 2018, a total of 155 head lice were collected from 49 individuals at the Medicals Centers of rural (Maférinyah village) and urban (Kindia city) areas, in Guinea. Specimens were subjected to a genetic analysis and pathogens screening using molecular tools. Results showed that all head lice belonged to eight haplotypes in the E haplogroup, with six newly identified for the first time. The study of the PHUM540560 gene polymorphisms of our clade E-head lice revealed that 82.5% exhibited the same polymorphism profile as the previously reported clade A-body lice. Screening for targeted pathogens revealed the presence of Acinetobacter spp., while sequencing highlighted the presence of several species, including Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter variabilis, Acinetobacter towneri and for the first time Acinetobacter haemolyticus. Our study is the first to report the existence of the Guinean haplogroup E, the PHUM540560 gene polymorphism profile as well as the presence of Acinetobacter species in head lice collected from Guinea.

Keywords: Acinetobacter haemolyticus; Acinetobacter spp.; Guinea; PHUM540560 gene; haplogroup E; head lice.

Figure 1

Map of head lice collection sites from infested individuals in two localities in Guinea.

Figure 2

Maximum-likelihood (ML) phylogenetic tree of the mitochondrial cytb gene showing the relationship of haplotypes identified in this study with other P. humanus haplotypes reported in the literature. Phylogenetic inference was conducted in MEGA 7 using the maximum likelihood method under the Kimura 2-parameter with 1000 bootstrap replicates. There were a total of 141 positions in the final dataset.

Figure 3

Cytb haplotype networks of human body and head lice including our samples. Each circle indicates a unique haplotype, and variations in circle size are proportional to haplotype frequencies. Pie colors and sizes in circles represent the continents and the number of their sequence for a haplotype. The length of the links between nodes is proportional to the number of mutations. The types of haplotypes identified in this study are underlined. Besides, all P. humanus lice were tested by multiplex qPCR targeting the PHUM540560 gene to investigate their ecotype; this method was used previously to distinguish between head and body lice belonging to clade A [41]. All our specimens were collected by the patients from their scalp hair, and belong to clade E. Using the multiplex qPCR method; all the 155 Guinean head lice specimens exhibited a FAM-labeled probe amplification specific to the body lice profile. These results confirm the fact that the PHUM540560- multiplex qPCR is a restricted molecular tool to differentiate only between clade A-human lice. Based on these data, we proceeded with the analysis of the PHUM540560 gene sequences of our samples and those belonging to clade A reported in the literature [41]. For this purpose, diverse human lice specimens encompassing both ecotypes were randomly selected from our lice collection. These samples were then subjected to standard PCR and sequencing of the targeted PHUM540560 gene. The obtained sequences were aligned with sequences of body and head lice. Alignment was conducted using the BioEdit v 7.0.5.3 software (available online: http://en.bio-soft.net/format/BioEdit.html). The rearranged sequences of the clade E Guinean-head lice PHUM540560 gene were revealed and to compared to the polymorphisms of the clade A body and head lice.

Figure 4

Alignments of a portion of Guinean head lice-Phum_PHUM540560 gene sequences with those from body and head lice reported in this study and previously in the literature. HL Amazonia [40] represent the 22 SNPs that are specific to clade A-head lice. BL Algeria (Alg) and Orlando represent the PHUM540560 gene profile specific to clade A-body lice. HL Guinea group contains 11 specimens: Orange block nucleotide represent 0 SNPs specific to head lice, blue block nucleotides represent 3 SNPs specific to head lice; green block nucleotides represent 18 SNPs specific to head lice and pink block nucleotides represents 20 SNPs that are specific to P.h. capitis. BL: body louse; HL: head louse; P.h.corporis strain USDA 1103172108290 Phum_PHUM540560 (gene sequence available in GenBank accession N. NW_002987859.1).

Figure 5

Phylogenetic tree highlighting the position of the Acinetobacter species identified in the head lice collected from Guinea compared to Acinetobacter spp. available in the GenBank database. Phylogenetic inferences were conducted in MEGA 7 using the maximum likelihood method based on the Kimura 2-parameter model for nucleotide sequences. Statistical support for internal branches of the tree was evaluated by bootstrapping with 1000 replicates. There was a total of 7 positions in the final dataset.