I Nyoman Mantik Astawa

Protective antibody response of Balb/c mice to Bali rabies virus isolate propagated in BHK-21 cells

The protective antibody response of Balb/c mice to Bali rabies virus (RABV) in BHK-21 cells was studied. The virus was isolated from a rabid dog and was adapted to replicate in BHK-21 cell culture for seven passages. The BHK-21-adapted Bali RABV (BHK-Bali RABV) was inactivated with binary ethylenimine and 24 mice were immunized twice at 21-days intervals with the inactivated virus and Rabisin® vaccine. Virus replication was detected using indirect immunofluorescence, immunocytochemistry, and western blotting assays. Enzyme-linked immunosorbent assay examination 2 weeks after the first immunization revealed RABV antibody titers that were mostly below the minimum protective level (<0.5 equivalent unit, EU). Antibody titers increased sharply after the second immunization. Antibody titers in serum of mice induced by inactivated BHK-Bali RABV one week after the second immunization were slightly lower (0.8–3.8 EU) than those induced by Rabisin vaccine (0.9–6.3 EU). RABV antibody titers were stable for at least 6 weeks after the second immunization. Both Rabisin vaccine and inactivated BHK-Bali RABV induced neutralizing antibodies with neutralization titers (50% protective dose per ml) of 29.84 for 0.1 ml Rabisin, 211.41 for 0.2 ml Rabisin, 27.41 for 0.1 ml BHK-Bali RABV, and 28.25 for 0.2 ml BHK-Bali RABV. Thus, inactivated BHK-Bali RABV induces a protective immune response in Balb/c mice, but at lower levels compared to induction by Rabisin vaccine.

Antioxidant properties of topical Caulerpa sp. extract on UVB-induced photoaging in mice

Caulerpa sp., a genus of seaweed native to the Indo-Pacific region, has been known for its antioxidant properties and health benefits when consumed as food. Previous studies have reported Caulerpa sp.’s potential as a strong antioxidant, but its effects on the skin in a topical preparation, especially its role in ultraviolet (UV) protection, have not been studied extensively. Our study investigated the protective effects of 0.2% and 0.4% Caulerpa sp. extract gels on photoaging in the UVB-irradiated skin of Wistar mice. The subjects were divided into naive control, vehicle control, and 3 treatment groups (0.2% Caulerpa sp. extract gel, 0.4% Caulerpa sp. extract gel, and 0.02% astaxanthin gel as a standard antioxidant). The groups, except the naive control group, received a total of 840 mJ/cm2 of UVB irradiation in four weeks. Protective effects of the extract were measured through the evaluation of collagen expression, matrix metalloproteinase (MMP)-1 expression and levels, and 8-OhDG expression. Mice who received topical application of Caulerpa sp. extract gel had higher collagen expression, better-preserved collagen structure, lower levels of MMP-1, and less MMP-1 and 8-OHdG expressions compared to the vehicle control group. There was no difference between different concentrations of the extract. Our findings demonstrated that topical application of Caulerpa sp. extract gel significantly protected UVB-irradiated mice skin from photoaging.