The Edmonston (Ed) strain of measles virus (MV) isolated in primary human kidney cells in 1954 has long been thought of as a representative MV strain. But this view has been challenged by wild-type MV strains isolated in marmoset B-lymphoblastoid B95a cells. Although the Ed strain is not pathogenic in monkey models, wild-type MV isolated in B95a cells from measles patients induces clinical signs typical of human measles, indicating that wild-type MV retains its pathogenicity. In addition, wild-type MV has restricted cell tropism and replicates only in B95a and some lymphocyte cell lines. This is in sharp contrast to the ability of the Ed strain to replicate in a variety of human cell lines. To understand the molecular basis for the pathogenicity and the cell tropism of wild-type MV, we have established a reverse genetics system based on a highly pathogenic wild-type MV strain (IC-B) isolated in B95a cells. By using this system, we have constructed recombinant wild-type and Ed strains of MV bearing heterologous envelope hemagglutinin (H) proteins, and we have examined roles of the H protein in determining the cell tropism. Our results clearly indicate that the MV cell tropism is determined by not only the H protein, but also other viral proteins. We thus propose the presence of another unidentified MV receptor on the surface of Vero cells.

A Plasmodium falciparum malaria blood stage antigen was isolated from in vitro parasite culture supernatant. The chemical composition of the antigen was studied by high-performance thin-layer chromatography, thin-layer chromatography, gas-liquid chromatography, and other chemical methods. Such analysis indicated it to be a glycophospholipid (GPL) and to be composed of xylose, mannose, galactose, and glucose linked to a phospholipid, but no inositol. The extracted and purified antigen’s sensitivity and specificity properties were assessed by laser immuno assay and enzyme-linked immunosorbent assay. The results of the sensitivity study showed a very high malaria antibody-binding response compared to other known antigens. The specificity study of GPL antigen with different nonmalarial samples showed no positive response within the limit of significance. This isolated GPL antigen appears to be better than other antigens.

This study examined the prevalence of atypical pathogens causing community-acquired pneumonia (CAP) in Korea. We collected sera and clinical data for a period of 1 year for the adult patients consecutively admitted to Chunchon Sacred Heart Hospital with CAP. The diagnosis was made using serologic methods to detect antibodies for Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella spp., Chlamydia psittaci, and Coxiella burnetii. Among 81 recruited patients, C. pneumoniae (n = 10, 12.3%) was the leading cause of illness, followed by M. pneumoniae (n = 7, 8.6%). One case of C. burnetii pneumonia was detected, but there were no cases of Legionella spp. or C. psittaci. Three cases of C. pneumoniae pneumonia were co-infected with either M. pneumoniae or C. burnetii. There was no significant difference between atypical pneumonia and non-diagnosed pneumonia in terms of clinical manifestations. In conclusion, of the atypical pathogens causing CAP, C. pneumoniae and M. pneumoniae appear to be the important etiologic pathogens in Korea.

We applied remote sensing using satellite images capable of obtaining data over a broad range, transcending national borders, as a method of rapidly, precisely, and safely increasing our understanding of the potential distribution of malaria. Our target region was the so-called Mekong malaria region on the Indochina Peninsula. As a malaria index, we used existing distribution maps of total reported malaria cases, malaria mortality, vivax malaria and falciparum malaria incidences, and so forth for 1997 and 1998. We produced monthly distribution maps of a normalized difference vegetation index (NDVI) with values of 0.2+, 0.3+, 0.35+, and 0.4+ using the geographical information system/remote sensing software based on the East Asia monthly NDVI maps of 1997. These maps were overlaid with various malaria index distribution maps, and cross-tabulations were carried out. The resulting maps with NDVI values of 0.3+ and 0.4+ matched the falciparum malaria distribution well, and we realized, in particular, that falciparum malaria is prevalent in regions in which NDVI values of 0.4+ continue for 6 months or more, while cases are fewer in regions with NDVI values of 0.4+ that continue for 5 months or less. It will be necessary in the future to examine the relationship between NDVI values and the habitats of the various vector mosquitoes using high-resolution satellite images and to implement detailed forecasts for malaria endemic areas by means of NDVI.

Human Fcγ receptor (Fcγ R) genes form a clustered gene family, which consists of Fcγ RIIA, IIB, IIC, IIIA, and IIIB genes, on chromosome 1q23. We previously reported that the Fcγ RIIA-131H/H genotype in combination with the Fcγ RIIIB-NA2 allele is associated with susceptibility to cerebral malaria, and that such an association can be caused by linkage disequilibrium (LD) between these polymorphisms and the primary associated gene(s) in this region. Fcγ RIIIA is known to exhibit the genetic polymorphism Fcγ RIIIA-176F/V coded for different affinity to IgG1 and IgG3. In this study, we examined a possible association between Fcγ RIIIA-176F/V polymorphism and severity of malaria in 462 adult Thai patients with Plasmodium falciparum malaria. The frequencies of Fcγ RIIIA-176V among patients with mild malaria, with non-cerebral severe malaria, and with cerebral malaria were 32.7%, 29.9%, and 36.3%, respectively. This polymorphism showed neither positive nor negative association with the severity of malaria. Thus, we concluded that the association of Fcγ RIIA-131H/R and Fcγ RIIIB-NA1/NA2 polymorphisms with cerebral malaria in Thailand is not due to the LD caused by Fcγ RIIIA-176F/V.

Leptospirosis is not commonly reported from the Salem district in central Tamil Nadu in India. In October 2000, a rice mill worker, who had fever and jaundice, tested positive in leptospiral IgM enzyme-linked immunosorbent assay (ELISA). Microbiological and serological investigations were performed on the patient, a sample population of the rice mill workers, and the animal and rodent populations living in the same premises. Leptospira was isolated from the patient about 2 weeks after the onset of symptoms when he had recovered from illness following a course of doxycycline. The isolate was serovar Icterohaemorrhagiae of serogroup Icterohaemorrhagiae. The patient also showed a fourfold rise in titers in microscopic agglutination test (MAT) and IgG ELISA. The rice mill workers had a seroprevalence rate of 68.3%, which was significantly higher than that among a control group consisting of persons engaged in other occupations. Serological studies conducted among cattle, dogs, cats, and rats showed seroprevalence rates of 52.9%, 50.0%, 66.6%, and 52.1%, respectively. Leptospires were isolated from two rats, but the isolates were lost during subculturing and could not be characterized. The most predominant serogroup identified by MAT was Autumnalis for rice mill workers and all animal populations. The other serogroups that reacted in MAT were Icterohaemorrhagiae, Australis, Grippotyphosa, and Patoc. Although Australis and Grippotyphosa showed agglutination in the case of human samples, none of the animals had detectable titers to these serogroups. The rice mills of Salem, having large rodent populations, various animals living in close proximity, a wet environment, and unprotected exposure of the workers to the environment, constitutes an ideal setting for transmission of leptospirosis and could be an epidemiological niche of leptospirosis.