Detection of Coxsackievirus B 4 antibodies in cases of suspected encephalopathy by microneutralization test.

A retrospective study of serum and cerebrospinal fluid (CSF) samples collected from suspected viral encephalitis and encephalopathy cases was carried-out and it included 100 CSF and 89 serum samples from Goa, collected during 1990-1994. These samples which were negative for antibodies to Japanese encephalitis (JE), West Nile (WN), Dengue-2 (DN-2) and herpes viruses, were tested for Coxsackievirus B 4 specific antibodies by 'in vitro' microneutralization technique along with 80 negative control serum samples. Out of 189 specimens (100 CSF and 89 serum), 23 CSF and 41 serum samples were positive for Coxsackievirus B 4 neutralizing antibodies. Antibody profile seemed to be IgG as revealed by mercaptoethanol treatment. The presence of neutralizing antibodies to coxsackievirus B 4 with titres as high as 1:512 in 8 CSF and 19 serum samples seemed to be suggestive of viral meningitis due to Cox B-4 viruses.

'In vitro' antiviral activity of neem (Azadirachta indica. A. Juss) leaf extract against group B coxsackieviruses.

The antiviral and virucidal effect of methanolic extract fraction of leaves of neem (Azadirachta indica A. Juss) (NCL-11) was studied regarding its activity and possible mechanism of action against Coxsackie B group of viruses. NCL-11 inhibited plaque formation in 6 antigenic types of Coxsackie virus B at a concentration of 1000 micrograms/ml at 96 hrs. 'in vitro'. Additionally virus inactivation, yield reduction and effect of time of addition assays suggested that NCL-11 was most effective against coxsackie virus B-4 as a virucidal agent besides interfering at an early event of its replicative cycle. The evidence suggested that presence of a battery of compounds besides flavonoids, triterpenoids and their glycosides in NCL-11 have antiviral action for coxsackie B group of viruses 'in vitro.' The minimal inhibitory concentrations were not toxic to Vero (African green monkey kidney), cells; subtoxic concentration was 8,000 micrograms/ml and cytotoxic concentration 10,000 micrograms/ml, which was confirmed by trypan blue dye exclusion test.

In vitro antiviral activity of indigenous glycyrrhizin, licorice and glycyrrhizic acid (Sigma) on Japanese encephalitis virus.

Glycyrrhizin, a triterpenoid glycoside and Licorice from Glycyrrhiza glabra and Ammonium salt of Glycyrrhizic acid (Sigma) were tested for antiviral activity on three strains of Japanese encephalitis virus (JEV), Nakayama, P-20778 and 821564 XY48. Purified glycyrrhizin (M.w. 822.92) inhibited plaque formation in all the three strains of JEV at a concentration of 500 micrograms/ml at 96 hrs, Similar effect was observed at 1000 micrograms/ml concentration with Licorice and Ammonium salt of glycyrrhizic acid. The minimal inhibitory concentrations were not toxic to porcine stable kidney (PS) and human cervical carcinoma (HeLa) cell lines. Cyctotoxicity of these chemicals was evaluated by trypan blue dye exclusion test which indicated subtoxic concentrations at 5,000 micrograms/ml at 96 hrs and toxic concentrations were 10,000 micrograms/ml at the same time period for the host cells PS. Thus the indigenously purified glycyrrhizin seems to be more potent antiviral agent than Licorice and ammonium salt of glycyrrhizic acid (Sigma) for JEV 'in vitro'.