Detection of circulating antigens and antibodies in Toxocara canis infection among children in Chengdu, China.

In order to determine the seroprevalence of Toxocara spp. infection in children from Chengdu, we performed an enzyme-linked immunosorbent assay (ELISA) and sandwich ELISA (S-ELISA) with excretory-secretory antigens isolated from second-stage larvae of Toxocara canis (TES-Ag ELISA). The seroprevalences of T. canis antibodies in the children from rural areas, urban districts, and urban districts with recent Ascaris lumbricoides infection were 17.7% (59/333), 2.1% (4/186), and 2.6% (1/38), respectively. Among 63 suspected patients with symptoms of T. canis infection, 31 had positive antibodies. The inhibition assay showed an apparent inhibiting capacity of TES-Ag for the antibody against T. canis larvae. The result of S-ELISA demonstrated that circulating antigens of T. canis larvae could be detected in part of the serum with positive antibodies and that the detection rate for circulating antigens in the sera could be improved by polyethylene glycol-acid treatment. This is the first epidemiological study to confirm the existence of T. canis infection and Toxocara-larvae migrans in Chengdu by the combination of TES-Ag ELISA and S-ELISA.

Localizations of NS3 and E proteins in mouse brain infected with mutant strain of Japanese encephalitis virus.

Infection with a mutant Japanese encephalitis virus (JEV) strain RP-2ms showed reduced neurovirulence than wild type or RP-9 strains after inoculation in BALB/c mice. However, higher intracellular viral titer was detected in Rp-2ms infected cultured cells. Localizations of non-structural 3 (NS3) and envelope (E) proteins were demonstrated by immunocytochemistry. NS3 protein was primarily found in the pyramidal neurons in cerebrum, in the molecular and granular layers of cerebellum. Neither E nor NS3 protein was detected in Purkinje cells of the cerebellum. Immunoelectron microscopic observations showed that E and NS3 proteins were positive in JEV-induced membranous systems, mainly hypertrophic rough endoplasmic reticulum (rER) and membrane vesicle structure (MVS) but not smooth membrane structure. Virus particles were seen in the Golgi apparatus, rER, nuclear envelope, MVS and cytoplasmic vacuoles. Different mechanisms of intracellular trapping in vivo provide a possible basis for attenuation of RP-2ms strains of JEV.