Critical Review: Cutting Edge: Immunity against a “ Silent” Salivary Antigen of the Lyme Vector Ixodes scapularis Impairs Its Ability to Feed (Kotsyfakis, Anderson and Andersen)
A. Overview of the Manuscript
Ixodes scapularis are ticks that transmit the bacteria Borrelia burgdorfer that is responsible for Lyme disease. Molecular characterization of antigens produced in the tick saliva is difficult because these antigens do not produce an immune response in the host. However, when guinea pigs were vaccinated with supraphysiological amounts of sialostatin L2, a component of tick saliva, infesting ticks showed decreased ability to feed, signs of inflammation, and increased rejection time. In animals that were not injected with the vaccine, no antibodies to sialostatin L2 were produced despite their repeated tick exposure. The study showed that: (1) sialostatin L2 has an important role in nymphal or tick infestation that can be blocked by host immunity and (2) immunity to sialostatin was only induced after vaccination with the protein.
B. Critical review of the manuscript
The abstract was able to present the rationale, objectives, methods, and results of the study. Conclusions, however, were not clearly stated. In the introduction, a concise summary was given about current knowledge of salivary antigens that pass on the pathogen Borrelia burgdorfer. Questions that arose out of the current knowledge served as the rationale for the study. Aims were not clearly stated in the introduction part. Instead, a summary of the research was given in the introduction. The use of standard methods meant that these techniques have already been reviewed and criticized by other researchers. Statistical analysis used was appropriate; ANOVA is appropriate for quantitative data like weight, number. The chi square tests were appropriate for qualitative data. The number of replications used was not directly mentioned, although Figure 1A was labelled to show that there were four animals in a treatment. It was not mentioned if this was number of samples or if one animal represented one replicate.
The presentation of the results was lengthy with a tendency to repeat the methodology. The text was continuous, (there were no subheadings), making it difficult to read and absorb the information given. The illustrations in the paper were not clear and uniform. Letters and axis titles were irregular and captions were very long. As an example, Figure 2A was very small and the legends were difficult to read. Nevertheless, the interpretation of the data was justified by the results with the study was discussed in the context of the previous research. The conclusion that some salivary components are undetectable by humoral immunity and that sialostatin L2 was a silent antigen (Ag) appeared to be correct. However, the authors failed to point out the future directions that have to be taken to characterize other silent antigens or determining the minimum titres needed for the vaccines to work.
C. Suggestions on how the study and manuscript could be improved upon
The study was able to adequately address the goal of producing an antibody response in host cells to the salivary antigens (in this case, sialostatin L2). The procedure in conducting the study was novel, simple, yet effective. However, the manuscript needs to be improved. Introduction should present the rationale for the study, background, and objectives concisely. The results portion should be focused on discussing the outcomes and the implications of these outcomes. Here, results were not presented very well. To improve the presentation, graphs must be drawn in a clear and stand-alone manner; meaning that anyone looking at the graph should be able to understand or see the results right away. Axis titles and legends should be properly indicated. Captions also have to be composed well to be effective in relaying information. The discussion must focus on the correlation and comparison of results to previous studies, and how future studies can be improved. The contribution of the results to current knowledge needs to be emphasized and if applicable, recommendation for future research direction should be made.
Work Cited
Kotsyfakis, Michalis, et al. ” Cutting Edge: Immunity Against a ” Silent” Salivary Antigen of the Lyme Vector Ixodes scapularis Impairs Its Ability to Feed.” The Journal of Immunology 181 (2008): 5209-5212.
