Recently, innate immune lymphocytes, such as natural killer (NK) T cells and γδ antigen receptor-bearing T (γδ T) cells, have garnered much attention, and their biological significance in the tumor immunity, allergic diseases and infectious diseases is extensively exploited. We have addressed the role of these cells in the host defense using a mouse model of pulmonary infection with Cryptococcus neoformans, which frequently causes fatal meningoencephalitis in AIDS patients. Host defense to this fungal pathogen is largely mediated by cellular immunity, and type-1 helper T (Th1) cells play a central role in this process. This infection causes a prompt accumulation of both NKT and γδ T cells in the lung tissues in a monocyte chemoattractant protein (MCP)-1-dependent or -independent manner, respectively. Genetic deletion of Vα14+ NKT cells ameliorates the Th1 response and clearance of microorganisms in the lungs, whereas these host protective responses are rather enhanced in mice lacking γδ T cells. Thus, in some aspect, these innate immune lymphocytes may coregulate the Th1-mediated response for induction of the moderate host defense. γδ T cells may act to keep the balance of Th1-Th2 responses in a proper manner by suppressing the exaggerated Th1 response caused by NKT cells. In this review, I describe the recent research development in the innate immune host defense against cryptococcal infection in respiratory organs with emphasis on our data in the regulatory role of NKT cells and γδ T cells.

The incidence of infection due to extended spectrum β-lactamases (ESBLs) producing Enterobacteriaceae has markedly increased in recent years. The traditional susceptibility methods lack sensitivity and/or specificity and this issue has prompted the search for an accurate test to detect the presence of ESBL. The present study included 300 bacterial strains and was undertaken to determine the prevalence of ESBL-producing strains. Here, compared three tests: a double disk synergy test (DDS), a three-dimensional test (3-D), and an inhibitor potentiated disk diffusion test (IPT); each test employed three different antibiotic discs, i.e., ceftazidime, ceftriaxone, and cefotaxime, in order to screen for ESBL strains. A strain was said to be an ESBL producer if it showed positive result(s) on any one of the three tests. The prevalence rate of ESBL in our hospital was 12.6% (38/300). IPT detected the most strains (34/38), followed by 3-D (23/38), and then DDS (15/38). The ceftriaxone disc was found to detect more ESBLs than either the ceftazidime or the cefotaxime disc.

In a lobar pneumonia model of Klebsiella pneumoniae, the immunoprotective role of free lipoploysaccharide (LPS) and liposome-incorporated LPS was studied. An alteration in the biological activity of the LPS molecule, in terms of its pyrogenicity and lethal toxicity, was observed on incorporation in the liposome. Compared at equal doses, liposome-incorporated LPS was found to be non-pyrogenic and 10 times less toxic than free LPS. Liposome-incorporated LPS was more effective in providing protection against K. pneumoniae induced lobar pneumonia in rats. The immunological mechanism underlying protection revealed involvement of both nonspecific and specific immune response. Alveolar macrophage activation was observed after 4 and 14 days of treatment with the free and liposome-entrapped forms of LPS, respectively. Specific immunity in terms of plaque-forming cells was seen with both forms of LPS. Delayed type hypersensitivity reaction was observed only with liposome-incorporated LPS. It is concluded that a non-toxic and immunogenic form of K. pneumoniae LPS can be obtained by incorporation of the native preparation into liposomes.

Human T-lymphotropic virus type I (HTLV-I) infection was investigated in 168 Japanese immigrants (64 males and 104 females) living in the Tome-Acu county located in the State of Para, Brazil. The serological screening was performed using an enzyme-linked immunosorbent assay, and showed the presence of anti-HTLV in four women whose ages ranged from 50 to 88. Confirmation of infection and discrimination HTLV typing was performed using a nested PCR on the extracted DNA targeting the pX region. In three of the samples, infection was confirmed to be HTLV-I. Sequencing HTLV-I 5'LTR and the RFLP pattern using DraI and SacI endonucleases indicated that the virus is a member of the Cosmopolitan group. These three women originated from the Kyushu region, though two of the corresponding HTLV-I strains were phylogenetically related to the Japanese subgroup and the third to the Transcontinental subgroup, which probably reflects the geographical origin of the infected individuals. The Japanese community residing in the northern Brazil apparently have not contributed to increase the prevalence of HTLV-I in the country.

The seroprevalence of toxoplasmosis among 505 of human immunodeficiency virus (HIV)/AIDS patients was 226 (44.8%; 95% CI 42.64 - 51.76): 27 (47.4%) and 199 (44.4%) showed Toxoplasma seropositivity with and without toxoplasmic encephalitis (TE), respectively (P < 0.05). The majority of these patients were in the 25-34 age group (44 versus 39%), male (86 versus 76%), and Chinese (49 versus 53%), though no statistical significance was found between the two. Significant differences between these two groups were noted, however, in terms of marital status, occupation, and present address. The heterosexual exhibited the most frequent behavior at risk for HIV infection, and accounted for 51 and 59% of patients with and without TE, respectively. Only 17/260 (6.5%) and 1/137 (0.7%) of them later acquired TE after receiving primary chemoprophylaxis (cotrimoxazole) and antiretroviral therapy including HAART (P < 0.05). Fifty-seven (11.3%) out of those 505 patients were diagnosed with AIDS-related TE. The most common clinical manifestation was headache (56%). The computed tomography scan findings showed most lesions to be multiple (96.4%), hypodense (66.7%), and in the parietal region (39.3%). Twenty-seven (47.4%) patients had chronic (latent) Toxoplasma infection as evidenced by seropositivity for anti-Toxoplasma (IgG) antibody. At the time of diagnosis, the range of CD4 cell count was from 0-239 with a median of 25 cells/cumm. We also found that a CD4 count of less than 100 cells/cumm was significantly associated with development of TE (P < 0.05). Clinical outcomes showed that among those who survived, 21 (36.8%), 16 (28.1%), and 2 (3.5%) of patients had completed treatment, transferred out, and were lost to follow up, respectively. Unfortunately, 18 (31.6%) of the cases were officially pronounced dead. Overall, 7 (12.3%) patients were detected as recurrent TE in this study.

Rotavirus gastroenteritis is a common childhood infection, but the exact morbidity of the disease is not well described in Japan. We aimed at estimating morbidity measures to determine the magnitude of rotavirus gastroenteritis. An estimate for acute infectious gastroenteritis of all causes, to which rotavirus gastroenteritis belongs, has been available since the enactment in 1999 of the Law concerning the Prevention of Infectious Diseases and Medical Care of Patients with Infectious Diseases. Using this estimate and another estimate for the detection proportion of rotavirus among outpatients with acute infectious gastroenteritis, we calculated the annual incidence, the age-specific annual incidence rate, and the cumulative risk by the age of 6 years for rotavirus gastroenteritis. The latter estimate was obtained by a meta-analysis of four independent studies previously performed in Japan. According to our estimates, approximately 800,000 children in Japan under the age of 6 years visit pediatric practices or the outpatient department of hospitals because of rotavirus gastroenteritis at a rate of 11 cases/100 persons/year, and one in two children will visit pediatricians before they go to primary school. Such pediatrician visits most frequently occur at the age of 1 year (27 cases/100 persons/year). Thus, the magnitude of the burden of rotavirus disease among Japanese children is substantial.

Methicillin-resistant Staphylococcus aureus (MRSA), known as a nosocomial pathogen, has been isolated from community-acquired infections since the 1980s. It has been reported that there are carriers of MRSA in the community although the rate of carriers is low and the most important risk factor of community-acquired carriage is hospitalization or referral to healthcare facilities. We attempted to investigate methicillin-resistant and methicillin-susceptible S. aureus colonization, respectively, in nasal and axillary swabs obtained from 500 patients without a history of hospitalization who were admitted to outpatient clinics and from 102 healthcare workers chosen as a control group. Of the patients, 9.4% had nasal S. aureus colonization without methicillin-resistant strains. Of the health care workers, 8.8% had S. aureus colonization without methicillin-resistant strains and only one worker had MRSA. The nasal carriage ratio of S. aureus in children was found to be 19.1% (22 of 115), and that in adults was 6.5% (25 of 385). The difference between the two age groups was determined as statistically significant (P = 0.006).

Laboratory bioassay of the essential oil extracted from an indigenous plant, Ipomoea cairica, commonly known as 'Railway creeper', was carried out against the larvae of four vector species of mosquitoes in order to evaluate its mosquito larvicidal effect. Bioassay test revealed that the essential oil of the plant possess remarkable larvicidal properties as it could induce 100% mortality in the larvae of Culex tritaeniorhynchus (100 ppm), Aedes aegypti (120 ppm), Anopheles stephensi (120 ppm), and Culex quinquefasciatus (170 ppm) mosquitoes at concentrations rangeing from 100 to 170 ppm. The LC₅₀ and LC₉₀ values estimated for Cx. tritaeniorhynchus, Ae. aegypti, An. stephensi, and Cx. quinquefasciatus were 14.8 and 78.3, 22.3 and 92.7, 14.9 and 109.9, and 58.9 and 161.6 ppm, respectively. The essential oil was found to be most highly toxic to the larvae of Cx. tritaeniorhynchus followed by Ae. aegypti, An. stephensi, and Cx. quinquefasciatus mosquitoes.

During the outbreak, from 16 January 2002 to 3 March 2002, nasopharyngeal secretions obtained from 35 pediatric patients under 2 years of age and suffering from acute respiratory disease were tested by VIDAS respiratory syncytial virus (RSV) assay (an automated enzyme-linked fluorescent immunoassay) and reverse transcription-polymerase chain reaction (RT-PCR). RSV antigen was detected in 16 specimens by VIDAS RSV assay, and 15 of these were confirmed by the RT-PCR. A total of 18 samples were found to be positive by RT-PCR. RSV subgroup B was identified by further restriction fragment length polymorphism analysis using AvaII and BglII endonucleases in 17 of 18 (94%) RT-PCR positive samples. These findings indicated that RSV subgroup B was highly dominant during an outbreak of RSV infection among children in Ankara. To our knowledge, this is the first outbreak due to dominant RSV subgroup B documented in Turkey.