Gunasekaran Palani

Cytotoxicity and Degree of Conversion of Orthodontic Adhesives

OBJECTIVES To test the hypothesis that there is no difference in the cytotoxicity related to the modes of polymerization of five commercially available orthodontic bonding resins, with and without an oxygen-inhibited layer (OIL), and to evaluate the degree of conversion (DC) of these resins and correlate this to cytotoxicity. MATERIALS AND METHODS Five commercially available orthodontic bonding resins were tested for cytotoxicity and DC. Thirty-six disks of standardized dimensions, for each resin, were used for cytotoxicity assessment. Half of them were washed with 99% acetone to remove the OIL (washed resins), and the remaining disks were left intact (intact resins). Glass disks were used as a control. Vero cells were exposed to intact and washed resins on day 1. Cell viability was determined by tetrazolium bromide reduction assay 1, 3, and 6 days after exposure. The DC of the adhesive specimens of each resin, prepared with a procedure identical to the clinical bonding process, was assessed by Fourier transform infrared spectroscopy. RESULTS Single-cured systems were comparatively less cytotoxic than dual-cured systems. With removal of the OIL, increased cell viability was noted only with two resins on all three days. Resins tested showed differences in DC. A positive correlation was demonstrated by two resins. CONCLUSION The hypothesis is rejected. Single-cured systems are superior to dual-cured systems in exhibiting comparatively less toxicity and higher DC. A significant positive correlation was not established between cytotoxicity and DC.

Molecular characterization of wild-type measles viruses in Tamil Nadu, India, during 2005–2006: Relationship of genotype D8 strains from Tamil Nadu to global strains

Molecular characterization of measles viruses is a valuable tool for measuring the effectiveness of measles control and elimination programmes. WHO recommends that virological surveillance be conducted during all phases of measles control to document circulation of indigenous strains and trace future importation. This report describes the genetic characterization of wild type measles viruses from Tamil Nadu, India isolated between January 2005 and January 2006. In the study, 304 suspected measles cases (292 from 56 outbreaks and 12 sporadic cases) were investigated. Blood samples were collected from suspected measles outbreaks and 11 suspected sporadic cases and tested for the presence of measles and rubella specific IgM. Based on serological results, 53 outbreaks were confirmed as measles, 2 as a combination of measles and rubella, and 1 negative for both. Eight sporadic cases were confirmed as measles and one as rubella. Throat swab and urine samples were collected for virus isolation and 28 isolates were obtained. Sequencing and analysis showed that 3 isolates belonged to genotype D4 and 25 to genotype D8. Comparison of the genotype D8 sequences from Tamil Nadu with previously reported genotype D8 sequences from India and abroad showed six distinct clusters with Tamil Nadu strains forming two clusters. This study has established baseline molecular data and is the first report that describes genetic diversity of circulating measles strains in Tamil Nadu, a state in India. D8 has multiple lineages and this has been linked with importation of measles into the USA and UK. J. Med. Virol. 84:348–357, 2012.

Development and evaluation of flavi-immunoglobulinM capture enzyme-linked immunosorbent assay

In this study, we report the evaluation of In-house flavi virus immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA), which can be used as a screening test to determine the infecting flavivirus serotype over the current serological methods. A panel of 88 sera (inclusive of well characterized dengue, Japanese Encephalitis (JE) and West Nile virus (WNV) positive and negative samples tested and confirmed by commercial kit) was used for evaluation of the kit. The sensitivity and specificity of the In-house capture assay versus the commercial kit for the sero-diagnosis of dengue was 100% and 87% respectively, for JE IgM, it was found to be 90% and 100% respectively, and for West Nile it was 87.5% and 90.9%. Based on the study, we concluded that this flavivirus-serotyping ELISA provides rapid results and may be used as an accurate alternate to other serological tests for the specific diagnosis of flavivirus infections.

Antiviral activity of Thiosemicarbazones derived from α-amino acids against Dengue virus†

The endemicity and seasonal outbreaks of Dengue disease in most tropical and subtropical countries underscores an urgent need to develop effective prevention and control measures. Development of a Dengue vaccine, which is complicated by the Antibody Dependent Enhancement effect (ADE), a viral inhibitor, seems prudent as it would inhibit the spread of the virus. In vitro methods such as MTT assay and plaque formation unit reduction assays were employed for screening the viral inhibitory property of α‐amino acid based Thiosemicarbazides. The results elicits that at concentrations not exceeding the maximum non cytotoxic concentration (MNCC), these compounds completely prevented Dengue virus infection in vero cells as indicated by the absence of cytopathic effects in a dose‐dependent manner. The high potency of Bz‐Trp‐TSC against all four types of Dengue virus infection elevates Thiosemicarbazide as a lead antiviral agent for Dengue disease. Screening small molecules for antiviral activity against the most rapidly spreading mosquito‐borne viral disease is being explored by several research groups. Our findings would help to augment the efforts to identify the lead compounds for antiviral therapy to combat the Dengue disease. J. Med. Virol. 89:546–552, 2017.

Epstein–Barr Virus DNAemia and co-occurrence with cytomegalovirus dnaemia in postrenal transplant recipients from a tertiary care center

Aim: Co-occurrence of Epstein–Barr virus (EBV) with Cytomegalovirus (CMV) is associated with an increased risk of EBV-associated posttransplant lymphoproliferative disorder (PTLD). Quantitation of EBV by real-time polymerase chain reaction (PCR) can aid the clinicians in the initiation of preemptive measures to improve the survival of the graft. Methods: The study was conducted among postrenal transplant recipients (PRTRs) who were attending the nephrology department from 2011 to 2016. Real-time quantitative PCR for EBV was performed in whole blood. PRTRs were classified into asymptomatic with altered renal parameters (Group A) and symptomatic (Group B), which were further subcategorized into Group B1 (fever with anemia, leukopenia, thrombocytopenia, or altered liver enzymes (any two), Group B2 (Group B1 + end-organ disease or only end-organ disease), and Group B3 (graft dysfunction [GDF]). The posttransplant period was also defined. DNA was extracted (Qiagen, Hilden, Germany) from whole blood, and real-time PCR was performed using QuantiTect multiplex PCR kit. Unpaired t-tests and ANOVA were used to analyze the data. Results: A total of 89 PRTRs were enrolled, of which 39.3% (n = 35) had EBV DNAemia, 43.1% during very late, 41.1% in late and 28.6% in immediate post transplant periods. EBV DNAemia ranged from 324 to 32,436 copies/ml. EBV DNAemia was found in 84% (n = 75) of symptomatic (Group B) and 16% (n = 14) of asymptomatic (Group A). Among the PRTRs with GDF (Group B3), 44% (n = 11/25) had EBV DNAemia of 2893.9 ± 1869 copies/ml. EBV DNAemia was considerably higher in PRTRs without GDF (8700.2 ± 9675.6 copies/ml) than PRTRs with GDF and the difference was statistically significant (P = 0.004). EBV DNAemia with CMV DNAemia among PRTRs was found in 21.3% (n = 19). Conclusion: High EBV DNAemia may precede PTLD or GDF; therefore, regular screening of EBV DNAemia is warranted. CMV and EBV DNAemia may also co-exist in PRTRs. As CMV is an immunomodulating virus, it increases the risk of opportunistic infections, especially EBV.

Genetic characterization of Chikungunya virus 2009 isolates from South India

Chikungunya Virus (CHIKV) is a single stranded positive sense enveloped RNA virus. Re-emergence of CHIKV caused a massive outbreak with severe clinical manifestation affecting multiple organs. The genetic diversity of CHIKV, which caused recurring outbreaks in India, was studied. Blood samples were collected from suspected human cases of CHIKV infection in Chennai, Tamil Nadu and three Northern districts of Kerala in Southern India during the CHIKV outbreak in 2009. A partial E2 gene segment was amplified by RT-PCR. Among 119 samples 37 samples were positive for CHIKV by RT-PCR. Phylogenetic analysis revealed that the isolated sequences belonged to Indian Ocean Lineage (IOL) of ECSA genotype. The mutational analysis revealed the presence of substitutions such as S299N, T312M, A344T, S375T, V386G, W339R and S375P in the current study. In addition, a novel mutation V386G was observed in all the sequences. Two isolates found with unique substitutions W339R and S375P are reported. The structural analysis of the wild type and mutant proteins revealed that the structural changes are accompanied by modification in the intraprotein interactions.

A novel indirect ELISA for diagnosis of dengue fever.

Background & objectives: Dengue fever (DF) is associated with significant morbidity and mortality in the tropical and sub-tropical regions of the world. Since there are no effective antiviral drugs for treatment, clinicians often rely on the accurate diagnosis of dengue fever to begin supportive therapy at early stages of the illness. The objective of this study was to develop an in-house dengue virus serotype 2 (DENV-2) non-structural protein- 5 (NS5) based indirect ELISA. Methods: DENV-2 was raised in Vero cells and the viral proteins were separated and subsequently the NS5 protein was eluted. Serum samples from primary and secondary dengue fever patients; and acute and convalescent samples from Japanese encephalitis (JE) and West Nile virus (WNV) cases were used to validate the ELISA. Results: The assay was found to be 100 per cent specific in detecting DENV-2 specific antibodies from patients serum. However, in terms of sensitivity, the assay could detect IgM antibodies only from 90 per cent of the primary dengue samples. The IgM/IgG ratio of the primary and secondary samples was 7.24 and 0.64, respectively. Interpretation & conclusions: The results indicate that the DENV-2 NS5 ELISA is dengue group specific and can be used to differentiate dengue infection from other circulating Flavivirus infections. This NS5 ELISA can also be used to distinguish between primary and secondary dengue fever on the basis of IgM/IgG ratios. Further studies with larger sample sizes and different DENV serotypes are required to validate the ELISA.