A microchip developed for detecting antibodies against plaque-derived antigens

Currently available Russia-made preparations intended for serological plague diagnostics are usually aimed at detecting antibodies to single bacterial antigens in the blood serum. To improve reliability of the data obtained, it is rational to use test systems to simultaneously quantify antibodies to several immunodominant Y. pestis antigens. An opportunity of using biochip technology for quantifying specific antibodies to Yersinia pestis antigens was investigated. To do this, 5 commercially available sera, 35 blood sera obtained from individuals vaccinated with live plague vaccine collected 1, 4, 5, 18 months after immunization, as well as 5 sera obtained from healthy donors were analyzed. The objective of this work was to develop a biological microchip (immunochip) for detecting antibodies specific to Y. pestis-derived antigens. In particular, amino-modified slides were sensitized by immunodominant Yersinia pestis-derived antigens: capsule antigen F1, lipopolysaccharide (LPS), main somatic antigen (MSA), fibrinolysin, and pestin PP. Diagnostic specificity and sensitivity of the immunochip were assessed by using the approved homoand heterologous immune-biological preparations and experimental animal sera. It was found that the immunochip demonstrated a 100% diagnostic efficiency. An opportunity of applying this immunochip to determine specific antibody profile in individuals vaccinated with live plague vaccine was estimated. A commercially available ELISA-AB-F1 of Yersinia pestis kit was used for comparison that allowed to detect antibodies to Y. pestis F1 antigen in 77.1% of vaccinated individuals within the examined time period covering between 1 to 18 months post-vaccination, at titer 1:160–1:2560. In contrast, using the immunochip resulted in detecting F1 antigen-specific antibodies in 91.4% of samples post-vaccination at titer 1:320–1:2560. Moreover, such immunochip additionally allowed to detect antibodies specific to the remainder of Y. pestis-derived LPS, MSA, pestin PP in 54.3%, 20%, 42% of vaccinated individuals, respectively. The percentage of positive seroconversion in individuals vaccinated with live plague vaccine was 77.1% based on the ELISA data, 91.4% — to the F1 antigen according to the immunochip data, and 94.3% — by analyzing an extended antigen panel. Combining multiple antigenic markers in our immunochip allowed to identify greater seroconversion among vaccinated people compared to a standard ELISA. Thus, the data obtained suggest that the proposed immunochip technology might be promising in assessing developing humoral immunity.

biochip, antibodies, antigens, plague, immunity