Multilocus Sequence Typing (MLST) Technique Applied To Reveal Transmission Characteristics On Cryptosporidium And Giardia

Cryptosporidium and Giardia are the most common zoonotic parasites, which can infect humans and a variety of animals causing infectious diseases named cryptosporidiosis and giardiasis, with the main clinical symptoms as diarrhea. Both parasitic disease outbreaks have been reported in many countries and regions of the world, posing a significant global public health risk. Because multilocus sequence typing (MLST) technique can analyze the genetic characteristics of subtypes from multiple gene targets, it is widely used in analysing population genetic structure and dynamic of subtypes transmission. However, to date, few studies of Crypt osporidium and Giardia distribution and transmission routes have been carried out in vulnerable population like children especially in welfare institutions, and the data on important anthropozoonotic species C. meleagridis is scant in population genetics and cross-species transmission.In this study,62C. meleagridis specimens from children, AIDS patients, and birds were characterized by sequence analysis of the small sub unit rRNA (SSU rRNA) gene and five polymorphic markers, including the gp60, CP47, MSC6-5, RPGR and TSP8genes. Unique subtypes of C. meleagridis ranged from8at gp60locus,3at the RPGR,3at the MSC6-5,2at TSP8to1at CP47. Intragenic linkage disequilibrium (LD) was strong and complete at all gene loci. Two major groups of subtypes were seen, with most subtypes belonging to group1. Within group1, there was no clear population segregation, and2of the14multilocus subtypes of C. meleagridis were found in both AIDS patients and birds. These results provide the first evidence of a clonal population structure of C. meleagridis and the likely occurrence of cross-species transmission of C. meleagridis between birds and humans.In this study,396children samples were collected from welfare center to characterize the distribution of Crypt osporidium and Giardia. Crypt osporidium was characterized by sequence analysis of SSU rRNA gene and seven polymorphic markers, including the gp60, CP47, CP56, MSC6-7, RPGR, DZ-HRGP and hsp70genes. Giardia was characterized by sequence analysis of three gene targets, including the tpi, bg and gdh genes. Among them,39(9.85%) were infected with Cryptosporidium, and120(30.30%) were infected with Giardia. Only one Cryptosporidium species C. hominis and one subtype IaA14R4were identified, and only one genotype A2was identified in Giardia. By analyzing the genotypes of Cryptosporidium with MLST technique on7targets, two genotypes were identified in16specimens, and15 specimens have the same genotype, only one specimen has one SNP. For Giardia,3MLGs were inentified with the MLST technique, including AII-1(83cases), AII-8(33cases) and AII-13(4cases) in120specimens. AII-1was advantage subtype in3batches, AII-8was only found in1st batch and3rd batch, AII-13was only found in1st batch. The distribution of these genotypes illustrate the multiple sources of Giardia in this welfare center, and AII-1genotype showing a stable trend in the spread. Combination of both higher prevalence of parasites, single feature of species/genotypes and age distribution, we conclude that the presence of Cryptosporidium and Giardia epidemic outbreaks in this welfare center.In conclusion, results of the study will help to illustrate the zoonotic characteristic of C. meleagridis and the epidemic characteristics of Cryptosporidium and Giardia in vulnerable children. In addition, this study will play an important role in promoting the multilocus sequence typing (MLST) technique in transmission research of Cryptosporidium and Giardia.