HBV Surface Antigen

A simple model is designed for an inductive immunosensor in which the magnetic particles are attached to the bioreceptors to form a sandwich on the surface of an inductor. The inductor consists of a coil covered on a silicon oxide wafer. The coil comprises 250 turns of a planar gold wire, which is approximately 200 nm thick and 392 mm long, placed in a circle with a diameter of 2 mm. The model is well characterised by controlling the geometrical and electrical parameters and also the permeability of the magnetic material. To evaluate the feasibility of the model for virus monitoring, a novel inductive immunosensor is designed and for the first time applied for the detection of hepatitis B surface antigen (HBsAg). At first, Fab ' segment of primary anti-HBsAg is immobilised on the coil. Then, the coil is exposed to HBsAg and the complex is introduced to a secondary antibody conjugated with magnetic particles to form an immune-sandwich. Finally, the influence of magnetic particles on the coil inductance is recorded and used as a signal for HBsAg detection. The magnetic inductive immunosensor showed specific responses toward HBsAg with the detection limit of 1 ng mL(-1), linear range of 1 to 200 ng mL(-1), and a sensitivity of 6 x 10(-4) mL ng(-1). The experimental results showed a very good agreement with simulation data indicating the compatibility of sensor sensitivity to the expected theoretical values.

In Italy, HDV infection endemicity has greatly decreased overtime. Migratory flow may change this scenario as migrants often come from high HDV endemicity areas. Here, we studied characteristics of HDV infection in Italy, particularly addressed to the birth area of subjects. Chronic HBsAg carriers consecutively referring to 9 units in Italy prospectively enrolled for a six-month period in 2019 were tested for anti-HDV by ELISA. Multiple logistic regression analysis was performed to identify anti-HDV positivity independent predictors. A total of 894 HBsAg-positive subjects were enrolled. Of them, 786 (87.9%) were tested for anti-HDV. Anti-HDV overall prevalence was 9.9% (6.4% in Italian natives and 26.4% in non-natives; P < .001). HDV-RNA was checked in 63 (80.8%) of the 78 anti-HDV+ subjects, and 49 (77.8%) tested positive. Compared to non-natives, Italians were more likely males (male/female 1.6 vs 0.6; P < .05) and older (median age 57 years vs 46 years; P < .05). Multivariate analysis showed that non-natives (OR = 6.02; CI 95% = 3.06-11.84) and cirrhosis (OR 9.6; CI 95% = 5.39-17.30) were independently associated with anti-HDV positivity. A remarkable changing pattern in some characteristics of anti-HDV-positive subjects was observed over 1987-2019: a decreasing male/female ratio, an increasing mean age and proportion of cirrhotic subjects. Anti-HDV prevalence decreased from 7.4% to 6.4% among Italians, increasing from 12.2% to 26.4% among non-natives during 2001-2019. Hence, HDV infection in Italians is further decreasing and mostly affects old people and subjects with advanced disease reflecting a survival effect. Conversely, non-natives are sixfold more likely anti-HDV-positive with an increasing trend. Migratory flow may be a new challenge for HDV infection at the beginning of the third millennium.