RESUMO
Chandipura virus (CHPV), a negative-stranded RNA virus of family Rhabdoviridae is endemic in Central India since 1965. The virus gained public health importance when it was held responsible for massive outbreak in 2003-2004 in Maharashtra, Telengana and Gujarat with case fatality rates ranging from 55 to 75% among children. We studied the stability of the virus as well as RNA persistence in samples stored at different temperatures for different periods. CHPV remained infective in sand flies and cell culture supernatants at 4 °C for 8 weeks. At 37 °C CHPV remained viable for 18 days when stored in infected cell supernatant (Minimum essential medium supplemented with 10% fetal bovine serum). However, in infected sand flies stored at 37 °C, the virus lost virulence within a week. CHPV RNA, though lost virulence, could be detected in virus exposed sand flies stored at 37 °C for 13 weeks by real time RT-PCR. Retaining virulence at 37 °C for 18 days in serum containing medium is a matter of concern for laboratories and hospital settings where clinical samples are handled. RNA persistence for prolonged periods in dead sand flies might help in surveillance studies of CHPV in sand flies and will help in resource constraint nations where cold chain management is a concern.
RESUMO
Chikungunya fever is self-limiting. However, neurological and hemorrhagic complications have been seen in recent outbreaks. The clinical manifestations of this disease are similar to those of dengue virus infection, indicating the need for differential diagnosis in areas such as India, which are endemic for both viruses. The aim of the present study was to develop monoclonal antibodies (MAbs) against Chikungunya virus (CHIKV) and assess their use in MAb-based IgM capture ELISA (MAC ELISA). The ELISA detects CHIKV-specific IgM antibodies, a marker of recent infection, in a patient's serum. One IgG1 and two IgM isotype hybrids were obtained. All of the subclones derived from the IgG1 hybrid recognized the C protein of CHIKV. The anti-C MAb ClVE4/D9 was the most promising as a detector antibody in MAC ELISA (C-MAb ELISA) yielding higher positive-to-negative (P/N) ratios. When compared with the CHIKV MAC ELISA kit developed by the National Institute of Virology (NIV), Pune (NIV MAC ELISA), the sensitivity of the test was 87.01 % with 100 % specificity. The positive and negative predictive values (PPV and NPV) were 100 % and 94.47 %, respectively. In precision testing, standard deviation (SD) and coefficient of variation (% CV) values of the C-MAb ELISA were within acceptable limits. The C-MAb ELISA detected anti-CHIKV IgM in serum of patients up to five months after the onset of infection, indicating that anti-C MAbs have strong potential for use in MAC ELISA to detect recent CHIKV infection.
