Growth Temperature Influence on Atomic-Layer-Deposited In2O3 Thin Films and Their Application in Inorganic Perovskite Solar Cells.

Recently, indium oxide (In2O3) thin films have emerged as a promising electron transport layer (ETL) for perovskite solar cells; however, solution-processed In2O3 ETL suffered from poor morphology, pinholes, and required annealing at high temperatures. This research aims to carry out and prepare pinhole-free, transparent, and highly conductive In2O3 thin films via atomic layer deposition (ALD) seizing efficiently as an ETL. In order to explore the growth-temperature-dependent properties of In2O3 thin film, it was fabricated by ALD using the triethyl indium (Et3In) precursor. The detail of the ALD process at 115-250 °C was studied through the film growth rate, crystal structure, morphology, composition, and optical and electrical properties. The film growth rate increased from 0.009 nm/cycle to 0.088 nm/cycle as the growth temperature rose from 115 °C to 250 °C. The film thickness was highly uniform, and the surface roughness was below 1.6 nm. Our results confirmed that film's structural, optical and electrical properties directly depend on film growth temperature. Film grown at ≥200 °C exhibited a polycrystalline cubic structure with almost negligible carbon impurities. Finally, the device ALD-In2O3 film deposited at 250 °C exhibited a power conversion efficiency of 10.97% superior to other conditions and general SnO2 ETL.

Peripheral immune tolerance by prolactin-induced protein originated from human invariant natural killer T cells.

invariant natural killer T (iNKT) cells have been reported to regulate a diverse set of immunological responses. iNKT cell dysfunction in cytokine secretion is linked to the development of autoimmunity, an immune response against its own tissue. Interestingly, CD4+ iNKT cells preferentially secrete regulatory cytokines. Here we investigated what kind of secreting factors of it are involved in dendritic cell (DC) maturation to regulate immune responses. We found one of them, prolactin induced protein (PIP), from the supernatants of cultured CD4+ iNKT cells. It was validated using RT-quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis. Subsequent analysis upon PIP treatment was performed using fluorescence-activated cell sorting (FACS) analysis. We identified PIP as one of strong candidates for inducing DC maturation, to similar level to lipopolysaccharide, an already known candidate molecule. Recombinant PIP recapitulated natural function, and induction of DC differentiation by both recombinant and purified PIP was blocked by anti-Toll-like receptor (TLR)2 antibody (Ab), but not by anti-TLR4/5 or anti-receptor Ab for advanced glycation end product Ab. Interestingly, PIP induced the differentiation of naïve T cells into CD4+ CD25+ Foxp3+ regulatory T cells and reduced the number of helper T (Th)1 and Th17 cells produced by Pam3CysSerLys4. Take in together, these results suggest that PIP is an important factor that mediates immunoregulation by iNKT cells through TLR2-mediated signaling.

Effects of winter skiing on stress, heart rate, apprehension, and enjoyment in collegiate students: a single randomized controlled trial.

This study investigated the effect of winter skiing on stress levels in collegiate students and also observed psychological factors related to heart rate, apprehension, and enjoyment. Two hundred thirty-eight male students were randomly classified into the control group (n=117) or the ski group (n=121). The control group received lectures on skiing; however, the ski group received practical ski training. Psychological measures included stress, apprehension, and enjoyment; physical measures included heart rate at pre- and postday. There were significant correlations between stress and apprehension (r=0.366) and stress and enjoyment (r=-0.441). Specifically, apprehension negatively correlated with enjoyment (r=-0.599). Between both groups, a significant interaction effect was found among stress, apprehension, and enjoyment. Moreover, compared with the control group, the ski group's stress and apprehension were significantly reduced, whereas the enjoyment was significantly enhanced. This study suggests that winter skiing is a suitable sport for reducing stress and providing a high level of enjoyment for collegiate students.

An improved reverse transcription loop-mediated isothermal amplification assay for sensitive and specific detection of serotype O foot-and-mouth disease virus.

A sensitive and specific swarm primer-based reverse transcription loop-mediated isothermal amplification (sRT-LAMP) assay for the detection of serotype O foot-and-mouth disease virus (FMDV) was developed and evaluated. The assay specifically amplified the VP3 gene of serotype O FMDV, but did not amplify the VP3 gene of other serotype FMDVs or any other viruses. The limit of detection of the assay was 102 TCID50/mL or 103 RNA copies/µL, which is 100 times lower than that of the RT-LAMP assay without swarm primers. The new assay is 10 times more sensitive than reverse transcription-polymerase chain reaction (RT-PCR) and is comparable to the sensitivity of real time RT-PCR (qRT-PCR). Evaluation of the assay using different serotypes of FMDV strains showed 100% agreement with the RT-PCR results. The previously reported serotype O FMDV-specific RT-LAMP assay did not detect 20 out of 22 strains of serotype O FMDVs, probably due to multiple mismatches between the primer and template sequences, showing that it is not suitable for detecting the serotype O FMDVs circulating in Pool 1 region countries, including Korea. In contrast, the developed sRT-LAMP assay with improved primers can rapidly and accurately diagnose serotype O FMDVs circulating in Pool 1 region countries and will be a useful alternative to RT-PCR and qRT-PCR.

Epidemiological Characteristics of Re-emerging Vivax Malaria in the Republic of Korea (1993-2017).

Historically, Plasmodium vivax malaria has been one of the most highly endemic parasitic diseases in the Korean Peninsula. Until the 1970s, vivax malaria was rarely directly lethal and was controlled through the Korean Government Program administered by the National Malaria Eradication Service in association with the World Health Organization's Global Malaria Eradication Program. Vivax malaria has re-emerged in 1993 near the Demilitarized Zone between South and North Korea and has since become an endemic infectious disease that now poses a serious public health threat through local transmission in the Republic of Korea. This review presents major lessons learned from past and current malaria research, including epidemiological and biological characteristics of the re-emergent disease, and considers some interesting patterns of diversity. Among other features, this review highlights temporal changes in the genetic make-up of the parasitic population, patient demographic features, and spatial distribution of cases, which all provide insight into the factors contributing to local transmission. The data indicate that vivax malaria in Korea is not expanding expo- nentially. However, continued surveillance is needed to prevent future resurgence.

Characterization of Echinostoma cinetorchis endoribonuclease, RNase H.

Echinostoma cinetorchis is an oriental intestinal fluke causing significant pathological damage to the small intestine. The aim of this study was to determine a full-length cDNA sequence of E. cinetorchis endoribonuclease (RNase H; EcRNH) and to elucidate its molecular biological characters. EcRNH consisted of 308 amino acids and showed low similarity to endoribonucleases of other parasites (<40%). EcRNH had an active site centered on a putative DDEED motif instead of DEDD conserved in other species. A recombinant EcRNH produced as a soluble form in Escherichia coli showed enzymatic activity to cleave the 3'-O-P bond of RNA in a DNA-RNA duplex, producing 3'-hydroxyl and 5'-phosphate. These findings may contribute to develop antisense oligonucleotides which could damage echinostomes and other flukes.

Discovery of Parasite Eggs in Archeological Residence during the 15th Century in Seoul, Korea.

During civil engineering construction near Sejong-ro, Jongro-ku, Seoul, cultural sites were found that are thought to have been built in the 15th century. This area was home to many different people as well as the leaders of the Yi dynasty. To gain further insight into the life styles of the inhabitants of the old capital, soil samples were collected from various areas such as toilets, water foundations, and drainage ways. Parasite eggs were examined by microscopy after 5 g soil samples were rehydrated in 0.5% trisodium phosphate solution. A total of 662 parasite eggs from 7 species were found. Species with the highest number of eggs found were Ascaris lumbricoides (n=483), followed by Trichuris trichiura (138), Trichuris vulpis (21), Fasciola hepatica (8), Clonorchis sinensis (6), Paragonimus westermani (4), and Metagonimus yokogawai (2). These findings indirectly indicate the food habits of the people in Yi dynasty.

Comparison of the diagnostic performance of microscopic examination with nested polymerase chain reaction for optimum malaria diagnosis in Upper Myanmar.

BACKGROUND: Accurate diagnosis of Plasmodium infection is crucial for prompt malaria treatment and surveillance. Microscopic examination has been widely applied as the gold standard for malaria diagnosis in most part of malaria endemic areas, but its diagnostic value has been questioned, particularly in submicroscopic malaria. In this study, the diagnostic performance of microscopic examination and nested polymerase chain reaction (PCR) was evaluated to establish optimal malaria diagnosis method in Myanmar. METHODS: A total of 1125 blood samples collected from residents in the villages and towns located in Naung Cho, Pyin Oo Lwin, Tha Beik Kyin townships and Mandalay of Upper Myanmar were screened by microscopic examination and species-specific nested PCR method. RESULTS: Among the 1125 blood samples, 261 samples were confirmed to be infected with malaria by microscopic examination. Evaluation of the 1125 samples by species-specific nested PCR analysis revealed that the agreement between microscopic examination and nested PCR was 87.3% (261/299). Nested PCR successfully detected 38 Plasmodium falciparum or Plasmodium vivax infections, which were missed in microscopic examination. Microscopic examinations also either misdiagnosed the infected Plasmodium species, or did not detect mixed infections with different Plasmodium species in 31 cases. CONCLUSIONS: The nested PCR method is more reliable than conventional microscopic examination for the diagnosis of malaria infections, and this is particularly true in cases of mixed infections and submicroscopic infections. Given the observed higher sensitivity and specificity of nested PCR, the molecular method holds enormous promise in malaria diagnosis and species differentiation, and can be applied as an effective monitoring tool for malaria surveillance, control and elimination in Myanmar.

"Preliminary Seroepidemiological survey of dengue infections in Pakistan, 2009-2014".

BACKGROUND: Dengue virus is the causative agent of dengue fever, a vector borne infection which causes self-limiting to life threatening disease in humans. A sero-epidemiological study was conducted to understand the current epidemiology of dengue virus in Pakistan which is now known as a dengue endemic country after its first reported outbreak in 1994. METHODS: To investigate the prevalence of dengue virus in Pakistan during 2009-2014, a total of 9,493 blood samples were screened for the detection of anti-dengue IgM antibodies using ELISA. Clinical and demographic features available with hospital records were reviewed to ascertain mortalities related to dengue hemorrhagic shock syndrome. RESULTS: Out of 9,493 samples tested, 37% (3,504) were found positive for anti-dengue IgM antibodies. Of the seropositive cases, 73.6% (2,578/3,504) were male and 26.4% (926/3,504) were female. The highest number (382/929; 41.1%) of sero-positive cases was observed among the individuals of age group 31-40 years. The highest number of symptomatic cases was reported in October (46%; 4,400/9,493), and the highest number of sero-positive cases among symptomatic cases was observed in November (45.7%; 806/1,764). Mean annual patient incidence (MAPI) during 2009-2014 in Pakistan remained 0.30 with the highest annual patient incidence (11.03) found in Islamabad. According to the available medical case record, 472 dengue related deaths were reported during 2009-2014. CONCLUSION: The data from earlier reports in Pakistan described the dengue virus incidence from limited areas of the country. Our findings are important considering the testing of clinical samples at a larger scale covering patients of vast geographical regions and warrants timely implementation of dengue vector surveillance and control programs. TRIAL REGISTRATION NUMBER: It is an epidemiological research study, so trial registration is not required.

Sequence conservation of Plasmodium vivax glutamate dehydrogenase among Korean isolates and its application in seroepidemiology.

BACKGROUND: Glutamate dehydrogenase of malaria parasites (pGDH) is widely used in rapid diagnostic tests for malaria. Variation in the pGDH gene among Korean isolates of Plasmodium vivax was analysed, and a recombinant pGDH protein was evaluated for use as antigens for the serodiagnosis of vivax malaria. METHODS: Genomic DNA was purified from blood samples of 20 patients and the pGDH gene of P. vivax was sequenced. Recombinant protein was prepared to determine the antigenicity of pGDH by enzyme-linked immunosorbent assay (ELISA). RESULTS: Partial sequence analysis of the P. vivax pGDH gene from the 20 Korean isolates showed that an open reading frame (ORF) of 1410 nucleotides encoded a deduced protein of 470 amino acids. The amino acid and nucleotide sequences were conserved among all the Korean isolates. This ORF showed 100% homology with P. vivax strain Sal-I (GenBank accession No. XP_001616617.1). The full ORF (amino acids 39-503), excluding the region before the intron, was cloned from isolate P. vivax Bucheon 3 (KJ726751) and subcloned into the expression vector pET28b for transformation into Escherichia coli BL21(DE3)pLysS. The expressed recombinant protein had a molecular mass of approximately 55 kDa and showed 84.8% sensitivity (39/46 cases) and 97.2% specificity (35/36 cases) in an ELISA. The efficacy of recombinant pGDH protein in seroepidemiological studies was also evaluated by ELISA using serum samples collected from 876 inhabitants of Gyodong-myeon, Ganghwa County, Incheon Metropolitan City. Of these samples, 91 (10.39%) showed a positive reaction with recombinant pGDH protein. Among the antibody-positive individuals, 13 (14.29%) had experienced malaria infection during the last 10 years. CONCLUSION: The pGDH genes of P. vivax isolates from representative epidemic-prone areas of South Korea are highly conserved. Therefore, pGDH is expected to be a useful antigen in seroepidemiological studies. It was difficult to identify the foci of malaria transmission in Gyodong-myeon based on the patient distribution because of the very low parasitaemia of Korean vivax malaria. However, seroepidemiology with recombinant pGDH protein easily identified regions with the highest incidence of malaria within the study area. Therefore, recombinant pGDH protein may have a useful role in serodiagnosis.

Role of dendritic cell maturation factors produced by human invariant NKT cells in immune tolerance.

In this study, we used the culture supernatant of iNKT cells to identify human myeloid DC maturation factors produced by human CD4+ iNKT cells. S100A8 had a strong maturation effect. Notably, the recombinant S100A8 protein displayed properties of DC maturation functioning, and the induction of DC differentiation by both the purified and the recombinant protein were blocked by anti-S100A8 and anti-TLR-4 mAbs. DC differentiation induced by anti-major histocompatibility complex class II/CD1d Ab, S100A8, or both was qualitatively indistinguishable from that induced by the coculture of DCs and iNKT cells or via culture supplementation with supernatants from activated CD4+ iNKT cells. S100A8 also induced CD4+/CD25+/Foxp3+ Treg cells from naïve T cells. S100A8 may contribute to DC differentiation by elevating transcription factors or activating transcription factor-2, heat shock factor-1, or both, in mature DCs. S100A8 is a novel candidate iNKT cell-dependent DC maturation factor.

Performance of the BacT Alert 3D System Versus Solid Media for Recovery and Drug Susceptibility Testing of Mycobacterium tuberculosis in a Tertiary Hospital in Korea.

BACKGROUND: Tuberculosis (TB) is a major health problem, and accurate and rapid diagnosis of multidrug-resistant (MDR) and extended drug-resistant (XDR) TB is important for appropriate treatment. In this study, performances of solid and liquid culture methods were compared with respect to MDR- and XDR-TB isolate recovery and drug susceptibility testing. METHODS: Sputum specimens from 304 patients were stained with Ziehl-Neelsen method. Mycobacterium tuberculosis (Mtb) isolates were tested for recovery on Löwenstein-Jensen (LJ) medium and the BacT Alert 3D system. For drug susceptibility testing of Mtb, isolates were evaluated on M-KIT plates and the BacT Alert 3D system. RESULTS: The recovery rates were 94.9% (206/217) and 98.2% (213/217) for LJ medium and the BacT Alert 3D system, respectively (kappa coefficient, 0.884). The rate of drug resistance was 13.4% for at least one or more drugs, 6.0% for MDR-TB and 2.3% for XDR-TB. M-KIT plate and BacT 3D Alert 3D system were comparable in drug susceptibility testing for isoniazid (97.7%; kappa coefficient, 0.905) and rifampin (98.6%; kappa coefficient, 0.907). Antibiotic resistance was observed using M-KIT plates for 24 of the total 29 Mtb isolates (82.8%). CONCLUSION: The liquid culture system showed greater reduction in the culture period, as compared with LJ medium; however, drug susceptibility testing using M-KIT plates was advantageous for simultaneous testing against multiple drug targets.

Population genetic structure and natural selection of apical membrane antigen-1 in Plasmodium vivax Korean isolates.

BACKGROUND: Plasmodium vivax apical membrane antigen-1 (PvAMA-1) is a leading candidate antigen for blood stage malaria vaccine. However, antigenic variation is a major obstacle in the development of an effective vaccine based on this antigen. In this study, the genetic structure and the effect of natural selection of PvAMA-1 among Korean P. vivax isolates were analysed. METHODS: Blood samples were collected from 66 Korean patients with vivax malaria. The entire PvAMA-1 gene was amplified by polymerase chain reaction and cloned into a TA cloning vector. The PvAMA-1 sequence of each isolate was sequenced and the polymorphic characteristics and effect of natural selection were analysed using the DNASTAR, MEGA4, and DnaSP programs. RESULTS: Thirty haplotypes of PvAMA-1, which were further classified into seven different clusters, were identified in the 66 Korean P. vivax isolates. Domain II was highly conserved among the sequences, but substantial nucleotide diversity was observed in domains I and III. The difference between the rates of non-synonymous and synonymous mutations suggested that the gene has evolved under natural selection. No strong evidence indicating balancing or positive selection on PvAMA-1 was identified. Recombination may also play a role in the resulting genetic diversity of PvAMA-1. CONCLUSIONS: This study is the first comprehensive analysis of nucleotide diversity across the entire PvAMA-1 gene using a single population sample from Korea. Korean PvAMA-1 had limited genetic diversity compared to PvAMA-1 in global isolates. The overall pattern of genetic polymorphism of Korean PvAMA-1 differed from other global isolates and novel amino acid changes were also identified in Korean PvAMA-1. Evidences for natural selection and recombination event were observed, which is likely to play an important role in generating genetic diversity across the PvAMA-1. These results provide useful information for the understanding the population structure of P. vivax circulating in Korea and have important implications for the design of a vaccine incorporating PvAMA-1.

Up-regulated S100 calcium binding protein A8 in Plasmodium-infected patients correlates with CD4(+)CD25(+)Foxp3 regulatory T cell generation.

BACKGROUND: The pro-inflammatory S100 calcium binding protein A8 (S100A8) is elevated in the serum of patients with Plasmodium falciparum malaria, but its function in Plasmodium vivax malaria is not yet clear. This function was investigated in P. vivax-infected patients in this study. METHODS: The level of S100A8 in the serum was measured with ELISA. Full amino acids of S100A8 were synthesized to verify the functions for maturation of immature dendritic cell (iDC) and evaluation of CD4(+)CD25(+)Foxp3(+) regulatory T (Treg) generation by mature DC (mDC). RESULTS: A higher amount of S100A8 was detected in vivax-infected patients (141.2 ± 61.849 ng/ml, n = 40) compared with normal control group (48.1 ± 27.384 ng/ml, n = 40). The level of S100A8 did not coincide with that of anti-malarial antibody measured by indirect fluorescent antibody test (IFAT) using parasite-infected red blood cells as antigen. Programmed death-ligand 1 (PD-L1) was up-regulated on the surface of iDCs following treatment with synthetic S100A8, not with synthetic MSP-1, AMA-1 and CSP, as compared to the expression seen for non-treated iDCs. The addition of red blood cells of infected patients to iDCs also elevated their surface expression of CD86. However, the serum levels of S100A8 decreased with increase in parasitaemia. DCs matured by sera containing S100A8 generated Treg cells from naïve T cells. The ratio of Treg cells generated was inversely proportional to the concentration of S100A8 in sera. CONCLUSIONS: Treg cells suppress the activity of cytotoxic T cells, which kill malaria parasites; therefore, the up-regulation of S100A8 in malaria patients may contribute to pathogen immune escape or tolerance.

Relationship between Antibody-Positive Rate against Plasmodium vivax Circumsporozoite Protein and Incidence of Malaria.

The relationship between anti- Plasmodium vivax circumsporozoite protein (CSP) antibody levels and the prevalence of malaria in epidemic areas of South Korea was evaluated. Blood samples were collected from inhabitants of Gimpo-si (city), Paju-si, and Yeoncheon-gun (county) in Gyeonggi-do (province), as well as Cheorwon-gun in Gangwon-do from November to December 2004. Microscopic examinations were used to identify malaria parasites. ELISA was used to quantitate anti-circumsporozoite protein (CSP) antibodies against P. vivax. A total of 1,774 blood samples were collected. The overall CSP-ELISA-positive rate was 7.7% (n=139). The annual parasite incidences (APIs) in these areas gradually decreased from 2004 to 2005 (1.09 and 0.80, respectively). The positive rate in Gimpo (10.4%, 44/425) was the highest identified by CSP-ELISA. The highest API was found in Yeoncheon, followed by Cheorwon, Paju, and Gimpo in both years. The positive rates of CSP-ELISA were closely related to the APIs in the study areas. These results suggest that seroepidemiological studies based on CSP may be helpful in estimating the malaria prevalence in certain areas. In addition, this assay can be used to establish and evaluate malaria control and eradication programs in affected areas.

Current situation of scrub typhus in South Korea from 2001-2013.

BACKGROUND: The bacteria Orientia tsutsugamushi is the causative agent of scrub typhus, mite-borne disease, which causes an acute febrile illness in patients. An epidemiologic study was conducted to understand the characteristics of scrub typhus in South Korea. FINDINGS: Reporting of tsutsugamushi disease is mandatory in South Korea since 1994. To investigate the prevalence of tsutsugamushi disease from 2001 to 2013, medical records from the Korea Center for Disease Control and Prevention were reviewed. In total, 70,914 cases were reported during 2001-2013. Of these, 37.16% (26,349) were male and 62.84% (44,565) were female. The highest number of cases was in the 60-69-year-old age group (19,484; 27.48%), and 72.22% (51,212) were in the 50-79-year-old age group. There were 65,100 cases (91.80%) reported during October (24,964; 35.20%) and November (40,136; 56.60%). An almost four-fold increase in the number of patients was observed in 2013 (10,485 cases) compared to 2001 (2,637 cases). The highest number of patients was reported in the Jeonbuk (9,425; 13.29%) and lowest in the Jeju (362; 0.51%). CONCLUSIONS: A rapid increase in the incidence of patients with tsutsugamushi disease was observed in most areas from 2001 to 2013, with the majority of cases reported in the western and southern coast.

Detection of antibodies against the CB9 to ICB10 region of merozoite surface protein-1 of Plasmodium vivax among the inhabitants in epidemic areas.

BACKGROUND: The purpose of this study was to examine the usefulness of the conserved block 9 (CB9) to interspecies conserved block (ICB10) region of Plasmodium vivax merozoite surface protein-1 (MSP-1 (ICB910)) as a serodiagnostic tool for understanding malaria transmission. METHODS: Antibody titre in the blood samples collected from the inhabitants of Gimpo city, Paju city and Yeoncheon county of Gyeonggi Province, as well as Cheorwon county of Gangwon Province, South Korea were determined by enzyme-linked immunosorbent assay (ELISA). Microscopic examination was performed to identify malarial parasites. RESULTS: MSP-1(ICB910) is encoded by a 1,212-bp sequence, which produced a recombinant protein with a molecular weight of approximately 46 kDa. Antibody titres in 1,774 blood samples were determined with the help of ELISA using purified recombinant MSP-1(ICB910). The overall ELISA-positive rate was 8.08% (n = 146). The annual parasite incidences (APIs) in the regions where the blood sampling was carried out gradually decreased from 2004 to 2005 (1.09 and 0.80, respectively). Yeoncheon county had the highest ELISA-positive rate (10.20%, 46/451). Yeoncheon county also had the highest API both in 2004 and 2005, followed by Cheorwon county, Paju city and Gimpo city. CONCLUSIONS: The MSP-1 (ICB910)-ELISA-positive rates were closely related to API in the geographic areas studied. These results suggest that sero-epidemiological studies employing MSP-1 (ICB910)-ELISA may be helpful in estimating the prevalence of malaria in certain geographic areas. MSP-1(ICB910)-ELISA can be effectively used to establish and evaluate malaria control and eradication programmes in the affected areas.

Seroprevalence of Plasmodium vivax in the Republic of Korea (2003-2005) using indirect fluorescent antibody test.

Plasmodium vivax reemerged in the Republic of Korea (ROK) in 1993, and is likely to continue to affect public health. The purpose of this study was to measure levels of anti-P. vivax antibodies using indirect fluorescent antibody test (IFAT) in border areas of ROK, to determine the seroprevalence of malaria (2003-2005) and to plan effective control strategies. Blood samples of the inhabitants in Gimpo-si, Paju-si, and Yeoncheon-gun (Gyeonggi-do), and Cheorwon-gun (Gangwon-do) were collected and kept in Korea Centers for Disease Control and Prevention (KCDC). Out of a total of 1,774 serum samples tested, the overall seropositivity was 0.94% (n=17). The seropositivity was the highest in Paju-si (1.9%, 7/372), followed by Gimpo-si (1.4%, 6/425), Yeoncheon-gun (0.67%, 3/451), and Cheorwon-gun (0.19%, 1/526). The annual parasite incidence (API) in these areas gradually decreased from 2003 to 2005 (1.69, 1.09, and 0.80 in 2003, 2004, and 2005, respectively). The highest API was found in Yeoncheon-gun, followed by Cheorwon-gun, Paju-si, and Gimpo-si. The API ranking in these areas did not change over the 3 years. The seropositivity of Gimpo-si showed a strong linear relationship with the API of 2005 (r=0.9983, P=0.036). Seropositivity data obtained using IFAT may be useful for understanding malaria prevalence of relevant years, predicting future transmission of malaria, and for establishing and evaluating malaria control programs in affected areas.

Polymorphic patterns of the merozoite surface protein-3ß in Korean isolates of Plasmodium vivax.

BACKGROUND: The merozoite surface protein-3ß of Plasmodium vivax (PvMSP-3ß) is one of the candidate antigens for blood stage malaria vaccine development. The polymorphisms in PvMSP-3ß have been reported in certain P. vivax isolates. However, the diversity of PvMSP-3ß throughout its global distribution has not been well understood. In this study, the genetic diversity and the effects of natural selection in PvMSP-3ß among P. vivax Korean isolates were analysed. METHODS: Blood samples were collected from 95 patients with vivax malaria in Korea. The region flanking full-length PvMSP-3ß was amplified by polymerase chain reaction and cloned into a TA cloning vector. The PvMSP-3ß sequence of each isolate was determined and the polymorphic characteristics and effects of natural selection were analysed using the DNASTAR, MEGA4, and DnaSP programs. RESULTS: Five different subtypes of PvMSP-3ß were identified based on single nucleotide polymorphisms (SNPs), insertions, and deletions. Although a high level of sequence diversity was observed in the PvMSP-3ß gene, the coiled-coil tertiary structure of the PvMSP-3ß protein was well conserved in all of the sequences. The PvMSP-3ß of Korean isolates is under natural selection. DNA polymerase slippage and intragenic recombination likely contributed to PvMSP-3ß diversity in Korean P. vivax isolates. CONCLUSIONS: The PvMSP-3ß of Korean P. vivax isolates displayed polymorphisms, with SNPs, insertions and deletions scattered throughout of the gene. These results of parasite heterogeneity are relevant to the development of a PvMSP-3ß based vaccine against P. vivax and the implementation of malaria control programmes in Korea.