Serological Detection of Antibodies against Anaplasma spp. in Cattle Reared in the Gyeongsangbuk-do, Korea.

Anaplasmosis is a tick-borne, non-contagious, zoonotic disease caused by Anaplasma spp., which include Anaplasma marginale, A. centrale, A. phagocytophilum, A. platys, A. ovis, and A. bovis. Recently, in Korea, the prevalence of Anaplasma spp. has been investigated in some animals, such as dogs, horses, goats, cats, and Korean water deer. In cattle, A. marginale is the most virulent species and regarded as the typical type of species. However, data on the seroprevalence of Anaplasma spp. in cattle in Korea during the last decade is limited. This study was designed to investigate the seroprevalence of bovine anaplasmosis in Korea. From 2010 to 2013, blood samples were collected from 568 cattle. Forty animals (7.0%) tested seropositive for Anaplasma spp. by cELISA. Despite that current bovine anaplasmosis seropositivity rate in the Gyeongsangbuk-do is lower than those in tropical countries, anaplasmosis needs to be regarded as a concerning disease. The identification of the specific Anaplasma species infecting cattle in this province requires additional molecular studies. Moreover, further monitoring and control programs for bovine anaplasmosis is required, and the information from this study will be beneficial to develop these programs.

Determination of multiple-clone infection at allelic dimorphism site of Plasmodium vivax merozoite surface protein-1 in the Republic of Korea by pyrosequencing assay.

Allelic diversity leading to multiple gene polymorphisms of vivax malaria parasites has been shown to greatly contribute to antigenic variation and drug resistance, increasing the potential for multiple-clone infections within the host. Therefore, to identify multiple-clone infections and the predominant haplotype of Plasmodium vivax in a South Korean population, P. vivax merozoite surface protein-1 (PvMSP-1) was analyzed by pyrosequencing. Pyrosequencing of 156 vivax malaria-infected samples yielded 97 (62.18%) output pyrograms showing two main types of peak patterns of the dimorphic allele for threonine and alanine (T1476A). Most of the samples evaluated (88.66%) carried multiple-clone infections (wild- and mutant-types), whereas 11.34% of the same population carried only the mutant-type (1476A). In addition, each allele showed a high frequency of guanine (G) base substitution at both the first and third positions (86.07% and 81.13%, respectively) of the nucleotide combinations. Pyrosequencing of the PvMSP-1 42-kDa fragment revealed a heterogeneous parasite population, with the mutant-type dominant compared to the wild-type. Understanding the genetic diversity and multiple-clone infection rates may lead to improvements in vivax malaria prevention and strategic control plans. Further studies are needed to improve the efficacy of the pyrosequencing assay with large sample sizes and additional nucleotide positions.

Diversity of vir Genes in Plasmodium vivax from Endemic Regions in the Republic of Korea: an Initial Evaluation.

Variant surface antigens (VSAs) encoded by pir families are considered to be the key proteins used by many Plasmodium spp. to escape the host immune system by antigenic variation. This attribute of VSAs is a critical issue in the development of a novel vaccine. In this regard, a population genetic study of vir genes from Plasmodium vivax was performed in the Republic of Korea (ROK). Eighty-five venous blood samples and 4 of the vir genes, namely vir 27, vir 21, vir 12, and vir 4, were selected for study. The number of segregating sites (S), number of haplotypes (H), haplotype diversity (Hd), DNA diversity (π and Θw), and Tajima's D test value were conducted. Phylogenetic trees of each gene were constructed. The vir 21 (S=143, H=22, Hd=0.827) was the most genetically diverse gene, and the vir 4 (S=6, H=4, Hd=0.556) was the opposite one. Tajima's D values for vir 27 (1.08530, P>0.1), vir 12 (2.89007, P<0.01), and vir 21 (0.40782, P>0.1) were positive, and that of vir 4 (-1.32162, P>0.1) was negative. All phylogenetic trees showed 2 clades with no particular branching according to the geographical differences and cluster. This study is the first survey on the vir genes in ROK, providing information on the genetic level. The sample sequences from vir 4 showed a clear difference to the Sal-1 reference gene sequence, whereas they were very similar to those from Indian isolates.

Distribution of Antibodies Specific to the 19-kDa and 33-kDa Fragments of Plasmodium vivax Merozoite Surface Protein 1 in Two Pathogenic Strains Infecting Korean Vivax Malaria Patients.

OBJECTIVES: Plasmodium vivax merozoite surface protein 1 (PvMSP1) is the most intensively studied malaria vaccine candidate. Although high antibody response-inducing two C-terminal fragments of PvMSP1 (PvMSP1-19 and PvMSP1-42) are currently being developed as candidate malaria vaccine antigens, their high genetic diversity in various isolates is a major hurdle. The sequence polymorphism of PvMSP1 has been investigated; however, the humoral immune responses induced by different portions of this protein have not been evaluated in Korea. METHODS: Two fragments of PvMSP1 were selected for this study: (1) PvMSP1-19, which is genetically conserved; and (2) PvMSP1-33, which corresponds to a variable portion. For the latter, two representative strains, Sal 1 and Belem, were included. Thus, three recombinant proteins, PvMSP1-19, PvMSP1-33 Sal 1, and PvMSP1-33 Belem, were produced in Escherichia coli and then tested by enzyme-linked immunosorbent assays using sera from 221 patients with vivax malaria. RESULTS: Of the 221 samples, 198, 142, and 106 samples were seropositive for PvMSP1-19, PvMSP1-33 Sal 1, and PvMSP1-33 Belem, respectively. Although 100 samples were simultaneously seropositive for antibodies specific to all the recombinant proteins, 39 and six samples were respectively seropositive for antibodies specific to MSP1-33 Sal 1 and MSP1-33 Belem. Antibodies specific to PvMSP1-19 were the most prevalent. CONCLUSION: Monitoring seroprevalence is essential for the selection of promising vaccine candidates as most of the antigenic proteins in P. vivax are highly polymorphic.