Development of a Simple, Peripheral-Blood-Based Lateral-Flow Dipstick Assay for Accurate Detection of Patients with Enteric Fever.

Enteric fever is a systemic infection caused by typhoidal strains of Salmonella enterica and is a significant cause of mortality and morbidity in many parts of the world, especially in resource-limited areas. Unfortunately, currently available diagnostic tests for enteric fever lack sensitivity and/or specificity. No true clinically practical gold standard for diagnosing patients with enteric fever exists. Unfortunately, microbiologic culturing of blood is only 30 to 70% sensitive although 100% specific. Here, we report the development of a lateral-flow immunochromatographic dipstick assay based on the detection of Salmonella enterica serovar Typhi (S Typhi) lipopolysaccharide (LPS)-specific IgG in lymphocyte culture secretion. We tested the assay using samples from 142 clinically suspected enteric fever patients, 28 healthy individuals residing in a zone where enteric fever is endemic, and 35 patients with other febrile illnesses. In our analysis, the dipstick detected all blood culture-confirmed S Typhi cases (48/48) and 5 of 6 Salmonella enterica serovar Paratyphi A blood cultured-confirmed cases. The test was negative in all 35 individuals febrile with other illnesses and all 28 healthy controls from the zone of endemicity. The test was positive in 19 of 88 individuals with suspected enteric fever but with negative blood cultures. Thus, the dipstick had a sensitivity of 98% compared to blood culture results and a specificity that ranged from 78 to 100% (95% confidence interval [CI], 70 to 100%), depending on the definition of a true negative. These results suggest that this dipstick assay can be very useful for the detection of enteric fever patients especially in regions of endemicity.

O-Specific Polysaccharide-Specific Memory B Cell Responses in Young Children, Older Children, and Adults Infected with Vibrio cholerae O1 Ogawa in Bangladesh.

Cholera caused by Vibrio cholerae O1 confers at least 3 to 10 years of protection against subsequent disease regardless of age, despite a relatively rapid fall in antibody levels in peripheral blood, suggesting that memory B cell responses may play an important role in protection. The V. cholerae O1-specific polysaccharide (OSP) component of lipopolysaccharide (LPS) is responsible for serogroup specificity, and it is unclear if young children are capable of developing memory B cell responses against OSP, a T cell-independent antigen, following cholera. To address this, we assessed OSP-specific memory B cell responses in young children (2 to 5 years, n = 11), older children (6 to 17 years, n = 21), and adults (18 to 55 years, n = 28) with cholera caused by V. cholerae O1 in Dhaka, Bangladesh. We also assessed memory B cell responses against LPS and vibriocidal responses, and plasma antibody responses against OSP, LPS, and cholera toxin B subunit (CtxB; a T cell-dependent antigen) on days 2 and 7, as well as days 30, 90, and 180 after convalescence. In all age cohorts, vibriocidal responses and plasma OSP, LPS, and CtxB-specific responses peaked on day 7 and fell toward baseline over the follow-up period. In comparison, we were able to detect OSP memory B cell responses in all age cohorts of patients with detectable responses over baseline for 90 to 180 days. Our results suggest that OSP-specific memory B cell responses can occur following cholera, even in the youngest children, and may explain in part the age-independent induction of long-term immunity following naturally acquired disease.

Biochemical analysis of two varieties of water chestnuts (Trapa sp.).

In this study, two varieties (Green and red) of water chestnuts (Trapa sp.) have been selected for their biochemical analysis as well as nutrient composition using standard methods. The proximate composition of green water chestnuts revealed moisture 62.5, ash 1.04, crude fiber 2.13%, total soluble sugar 0.92%, reducing sugar 0.33%, non-reducing sugar 0.59%, starch 8.7%, lipid 0.84%. One hundred gram of green variety contained water soluble protein 0.275 mg, beta-Carotene 60 microg, vitamin-C 1.1 mg and total phenol 0.5 mg. The minerals contents of green variety were potassium 5.22%, sodium 0.64%, calcium 0.25%, phosphorus 6.77%, sulpher 0.38%, and iron, copper, manganese and zinc 200, 430, 90 and 600 ppm, respectively. The red variety contained moisture 62.7%, ash 1.30%, crude fiber 2.27%, total soluble sugar 0.90%, reducing sugar 0.30%, non-reducing sugar 0.60%, starch 8.2%, lipid 0.83%. The red variety contained water soluble protein 0.251 mg, beta-Carotene 92 microg, vitamin-C 0.9 mg and total phenol 0.60 mg per 100 g. The red variety contained potassium 5.32%, sodium 0.59%, calcium 0.26% phosphorus 6.77%, sulpher 0.32%, Iron 200 ppm, copper 450 ppm, manganese 110 ppm and zinc 650 ppm. The free amino acids, glutamic acid, tryptophan, tyrosine, alanine, lysine and leucine were commonly found in both varieties. In addition, green and red variety contained cysteine, arginine and proline and glutamine and asparagines, respectively. Thus, the present study sheds light on the nutrient contents of the two varieties of water chestnuts and suggests that water chestnuts may play a crucial role in human nutrition.