Changes in Histopathological and Serological Findings of the Liver after Treatment in Rabbit Clonorchiasis

In order to elucidate the recovery course and the residual change of clonorchiasis after praziquantel treatment, the changing pattem of histopathological findings of the liver, along with the serological, biochemical and hematological parameters, were evaluated in experimental rabbit clonorchiasis. Twenty rabbits were infected each with 300 metacercariae of Clonorchis sinensis and treated with praziquantel 200 mg/kg 14 weeks after infection. Until one year after infection, a Widening of the bile ducts, proliferation of biliary epithelium, and periductal fibrosis were observed in the liver, although the lesions became much milder than those of the untreated rabbits. The levels of anti-e. sinensis IgG antibody in the sera by EUSA decreased continuously after treatment. Biochemical items and hematological parameters showed no consistent changing pattem after infection or after treatment. It can be suggested that the histopathological lesions of rabbit cionorchlais, i.e., duct dilatation, hyperplasia of biliary epithelium and periductal fibrosis, may be hardly reversible. However, the level of circulating specific IgG antibody decreased significantly according to the healing process of inflammation

Ultrastructure of Cryptosporidium parvum Found in the Small Intestine of Immunosuppressed Mice

The ultrastructure of various stages of Cryptosporidium parvum was observed by transmission electron microscopy. C. parvum infection was activated in the small intestine of Korean laboratory mice (fCR) by immunosuppression with prednisolone for 7 weeks. The oocyst discharge was confirmed by modified Kinyon's acid fast stain of fecal specimens. Various endogenous stages of parasites, i. e., trophozoites, meronts, merozoites, and macrogametocytes, were observed in the middle part of the small intestine, as an extracytoplasmic but intracellular parasite of host mucosal epithelial cells. In trophozoites, a large nucleus with a prominent nucleolus was seen, and as they developed into meronts, endoplasmic reticulum appeared prominently in the cytoplasm. Two kinds of meronts, type I and type II, with eight and four merozoites respectively, were found. New merozoites were produced by nuclear division and external budding of the residual body of the meronts. The merozoites were lined with two unit membranes, unlike C. muris that has three membranes, and a nucleus was located near the posterior end. Mature merozoites had conoids, rhoptries and numerous micronemes; the characteristic structures of coccidian parasites. Macrogametocytes were largely vacuolated and "wall-forming body I" was recognized. Other sexual stages were difficult to recognize from our specimens. The present study confirmed that the Cryptosporidium found in the small intestine of Korean laboratory mice has a characteristic ultrastructure consistent with C. parvum

Population Structure and Transmission Dynamics of Plasmodium vivax in the Republic of Korea Based on Microsatellite DNA Analysis

Vivax malaria is widely prevalent, mainly in Asia and South America with 390 million reported cases in 2009. Worldwide, in the same year, 2.85 billion people were at risk. Plasmodium vivax is prevalent not only in tropical and subtropical areas but also in temperate areas where there are no mosquitoes in cold seasons. While most malaria researchers are focusing their studies on the parasite in tropical areas, we examined the characteristics of P. vivax in South Korea (temperate area) temporally, using 10 highly polymorphic microsatellite DNA (a short tandem repeat DNA sequence) in the parasite genome, and highlighted the differences between the tropical and temperate populations. We found that the South Korean P. vivax population had low genetic diversity and low recombination rates in comparison to tropical P. vivax populations that had been reported. We also found that some of the parasite clones in the population were changing from 1994 to 2008, evidence suggesting the continual introduction of the parasite from other populations, probably from North Korea. Polymorphic DNA markers of the P. vivax parasite are useful tools for estimating the situation of its transmission in endemic areas

Molecular Genetic Characterization of the Merozoite Surface Protein 1 Gene of Plasmodium vivax from Reemerging Korean Isolates▿

Plasmodium vivax merozoite surface protein 1 (PvMSP-1) has been considered a major candidate for the development of an antimalaria vaccine, but the molecule exhibits antigenic diversity among isolates. The extent of genetic polymorphism in the region between interspecies conserved blocks 4 and 5 (ICB4 and ICB5) of the PvMSP-1 gene was analyzed for 30 Korean isolates. Two genotypes, SK-A and SK-B, were identified on the basis of amino acid substitution. Almost all the amino acid sequences of the Korean isolates were nearly identical to those of the Solomon Island isolate Solo-83 (97.8 to 99.9% similarity) and Philippine isolates Ph-79, Ph-52-2, and Ph-49 (97.3 to 99.8% similarity). Also, we report two sequences in the isolates that were characterized on the basis of restriction fragment length polymorphism (RFLP). The RFLP profiles following digestion with the DraI restriction enzyme produced two distinguishable patterns. This study might be the first report of the region between ICB4 and ICB5 of the MSP-1 gene of P. vivax in South Korea

Single-Chain Antibody Fragment Specific for Plasmodium vivax Duffy Binding Protein▿

Phage display of single-chain variable fragment (scFv) antibodies is a powerful tool for selecting important, useful, and specific human antibodies. We constructed a library from three patients infected with Plasmodium vivax. Panning on recombinant PvRII enriched a population of scFvs that recognized region II of the P. vivax Duffy binding protein (DBP). Three clones of scFvs that reacted with PvRII were selected, and their biological functions were analyzed. These scFvs inhibited erythrocyte binding to DBP. Clone SFDBII92 had the greatest affinity (dissociation constant = 3.62 × 10−8 M) and the greatest inhibition activity (50% inhibitory concentration ≈ 2.9 μg/ml) to DBP. Thus, we demonstrated that human neutralizing antibody could be made from malaria patients using phage display and that these neutralizing scFvs should prove valuable for developing both passive and active immunization strategies based on DBP

Relationships among the 40 haplotypes of <i>P. vivax</i> (n = 87) in South Korea estimated by eBURST analysis.

<p>Relationships among 40 microsatellite haplotypes in the 87 isolates collected in South Korea as defined by eBURST analysis <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001592#pntd.0001592-Feil1" target="_blank">[32]</a>. H1, H2, … H40 represent the microsatellite haplotype. Red numbers represent the number of isolates that showed the haplotype. When the haplotype was found in only one isolate, the red number was omitted. Numbers in parentheses represent the year the haplotype was observed. H6 and H7 were included in the analysis but were classified into a different group because they were considerably different from others and were omitted from <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0001592#pntd-0001592-g004" target="_blank">Figure 4</a>.</p

Forty haplotypes of the <i>P. vivax</i> population in South Korea based on 10 microsatellite DNA loci.

<p>H: Haplotype, Numbers show number of isolates. Total: Total No. of isolates, Two predominant haplotypes, and H25 are highlighted in bold and the other haplotypes are highlighted in italic.</p