Antibody and memory B cell responses to the dengue virus NS1 antigen in individuals with varying severity of past infection

To further understand the role of NS1-specific antibodies (Abs) in disease pathogenesis, we compared neutralizing antibody levels (Nabs), NS1-Ab levels, IgG antibody subclass profiles and NS1-specific memory B-cell responses (Bmems) in individuals, with varying severity of past dengue. Nabs (Neut50 titres) were assessed using the Foci Reduction Neutralization Test (FRNT) and in-house ELISAs were used to assess NS1-Abs and NS1-Ab subclasses for all four DENV serotypes in individuals with past DF (n = 22), those with past DHF (n = 14) and seronegative (SN) individuals (n = 7). B-cell ELISpot assays were used to assess NS1-specific Bmem responses. 15/22 (68.18%) individuals with past DF and 9/14 (64.29%) individuals with past DHF had heterotypic infections. Neut50 titres were found to be significantly higher for DENV1 than DENV2 (p = 0.0006) and DENV4 (p = 0.0127), in those with past DHF, whereas there was no significant difference seen in titres for different DENV serotypes in those with past DF. Overall NS1-Ab to all serotypes and NS1-specific IgG1 responses for DENV1, 2 and 4 serotypes were significantly higher in those with past DHF than individuals with past DF. Those with past DHF also had higher IgG1 than IgG3 for DENV1 and DENV3, whereas no differences were seen in those with past DF. Over 50% of those with past DF or DHF had NS1-specific Bmem responses to >2 DENV serotypes. There was no difference in the frequency of Bmem responses to any of the DENV serotypes between individuals with past DF and DHF. Although the frequency of Bmem responses to DENV1 correlated with DENV1-specific NS1-Abs levels (Spearman r = 0.35, p = 0.02), there was no correlation with other DENV serotypes. We found that those with past DF had broadly cross-reactive Nabs, while those with past DHF had higher NS1-Ab responses possibly with a different functionality profile than those with past DF. Therefore, it would be important to further evaluate the functionality of NS1-specific antibody and Bmem responses to find out the type of antibody repertoire that is associated with protection against severe disease.     

Wuchereria bancrofti: detection of microfilariae in asymptomatic microfilaremic individuals with Setaria digitata antigens

A dot-ELISA for detection of microfilariae of Wuchereria bancrofti in an endemic area was developed. This test can differentiate the endemic normals from the microfilaraemic asymptomatic individuals. Antigens of molecular weight 130 and 52 kDa of the cattle filaria worm Setaria digitata were used for this test. It was observed that these two antigens were also present in the serum of asymptomatic microfilaraemic individuals.     

A simple and rapid non-radioactive oligonucleotide based hybridization assay for the detection of Wuchereria bancrofti

Five biotin labeled oligonucleotides was designed based on a previously cloned and characterized repetitive DNA sequence specific for Wuchereria bancrofti. The oligonucleotide mix (containing five probes) when used in a hybridization assay, detected as little as 100 pg of purified W. bancrofti, microfilarial DNA, a single infective stage larva and a single microfilaria in 50 microl blood sample. A simple protocol was followed for the hybridization assay. Blood samples lysed with sterile distilled water and digested with proteinase K in the presence of a detergent were directly applied on to nylon membranes for dot blot assays. The DNA extract of mosquitos carrying infective stage larvae was eluted through sephadex G-50 minicolumns prior to blotting. The assay was also able to detect DNA extracted from microfilariae infected samples stored over five days at room temperature (28 degrees C). This simple and rapid oligonucleotide hybridization protocol with the highly sensitive chemiluminescent-based detection has significant potential for the development of a field kit to detect W. bancrofti infection.     

Serum protein binding of antiepileptic drugs in Sri Lankans

The percentage protein binding of antiepileptic drugs was investigated in epileptic patients (n = 90) undergoing treatment with phenobarbitone, phenytoin and carbamazepine either as a single drug therapy or in different combinations. When administered individually, the percentage (mean +/- SEM) protein binding of phenobarbitone, phenytoin and carbamazepine were 50.84 +/- 7.03, 87.23 +/- 2.98 and 76.80 +/- 6.30 respectively. Combination of phenobarbitone and phenytoin resulted in percentage (mean +/- SEM) protein binding of 51.94 +/- 6.09 for phenobarbitone and 83.54 +/- 7.01 for phenytoin, while the combination of phenobarbitone and carbamazepine resulted in percentage (mean +/- SEM) protein binding of 49.60 +/- 2.59 for phenobarbitone and 79.10 +/- 3.31 for carbamazepine. When phenytoin was given with carbamazepine percentage (mean +/- SEM) protein binding was 87.22 +/- 4.48 for phenytoin and 72.50 +/- 5.92 for carbamazepine.     

Whole-genome analysis of a human rabies virus from Sri Lanka

The complete genome sequence of a human rabies virus, strain H-08-1320, from Sri Lanka was determined and compared with other rabies viruses. The size of the genome was 11,926 nt, and it was composed of a 58-nucleotide 3?? leader, five protein genes ?C N (1353 nt), P (894 nt), M (609 nt), G (1575 nt), and L (6387 nt) ?C and a 70-nt 5?? trailer. The intergenic region G?CL contained 515 nt. The sizes of the nucleoprotein, phosphoprotein, matrix-protein, glycoprotein and large-protein was 450, 296, 202, 524 and 2,128 residues, respectively. The phosphoprotein and large protein were one amino acid shorter and longer, respectively, than those of most rabies viruses. The glycoprotein of H-08-1320 had a unique amino acid substitution at antigenic site I. Whole-genome phylogenetic analysis showed that strain H-08-1320 formed an independent lineage and did not cluster with rabies viruses from other countries.     

Antimicrobial susceptibility and serotypes of Neisseria meningitidis and Streptococcus pneumoniae in Sri Lanka: Experience from the National Reference Laboratory

Objective: To determine the antimicrobial susceptibility and serotypes of Neisseria (N.) meningitidis and Streptococcus (S.) pneumoniae in Sri Lankan patients. ...     

The influence of three acid modifications on the physicochemical characteristics of tea-waste biochar pyrolyzed at different temperatures: a comparative study

Tea-waste is an abundant feedstock for producing biochar (BC) which is considered to be a cost effective carbonaceous adsorbent useful for water remediation and soil amendment purposes. In the present study, tea-waste BC (TWBC) produced at three different temperatures were subjected to nitric, sulfuric and hydrochloric acid modifications (abbreviated as NM, SM and HM respectively). Characteristics of the raw and modified BC such as ultimate and proximate analyses, surface morphology, surface acidity and functionality, point of zero charge, cation exchange capacity (CEC) and thermal stability were compared to evaluate the influence of pyrolysis temperature and of modifications incorporated. The amount of carboxylic and phenolic surface functionalities on TWBC was seen to decrease by 93.44% and 81.06% respectively when the pyrolysis temperature was increased from 300 to 700 °C. Additionally, the yield of BC was seen to decrease by 46% upon the latter temperature increment. The elemental analysis results provided justification for high-temperature BC being more hydrophobic as was observed by the 61% increase in H/C ratio which is an indication of augmented aromatization. The CEC was the highest for the low-temperature BC and was seen to further increase by NM which is attributed to the 81.89% increase in carboxylic functionalities. The surface area was seen to significantly increase for BC700 upon NM (∼27 times). The SM led to pore wall destruction which was observed in scanning electron microscopy images. Findings would enable the rational use of these particular modifications in relevant remediation and soil amendment applications.

Tea-waste biochar produced under different pyrolysis temperatures were subjected to three acid modifications and a comparative evaluation of their key physicochemical characteristics made.