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closeConcern about sporozoite motility conclusions
Posted by Vanderberg on 03 Sep 2010 at 14:51 GMT
This paper describes a novel antigen CelTOS that may prove to be useful for vaccination against pre-erythrocytic stages. The vaccination results are extremely encouraging. I am unconvinced, however, about the data describing the effects of antibodies on motility of sporozoites. Conceivably, the authors’ conclusions could turn out to be correct but they have not demonstrated this in the current paper. Our techniques describing tracks left behind by motile sporozoites were published as a qualitative and not a quantitative procedure (Ref. 12 in the present paper), although others have chosen (erroneously in my opinion) to use this procedure for quantification of sporozoite motility. The problem is that sporozoites that do not settle and attach cannot leave tracks. Thus, this approach does not give reliable quantitative results; it records only that subset of sporozoites able to settle and remain attached to a slide during incubation. This likely skews data because non-attached sporozoites are washed off and not recorded. For quantification of motility, we prefer to assess a sample of all sporozoites in a given medium by videorecording actual motility within samples over a defined time. This allows us to assess and quantify motility at leisure after the experiments, either by viewing videos or total projections prepared from them (Kebaier and Vanderberg. (2009). Initiation of Plasmodium sporozoite motility by albumin is associated with induction of intracellular signaling. Int. J. Parasitol. 40:25.). Motility needs to be measured by measuring motility; this should be done for all sporozoites within a sample, not by counting tracks left by a subset of the sporozoite population. Our own studies have shown poor correlation between counting tracks and observing the actual motility of sporozoites
RE: Concern about sporozoite motility conclusions
ElkeBergmann replied to Vanderberg on 09 Sep 2010 at 00:04 GMT
We, in essence, agree with the comment posted by Dr.Vanderberg concerning the caveat associated with counting trails and quantify the motility activity. Initially, we had used the motility assay as intended by the cited ref.12 in a qualitative manner. However, one of the reviewers felt that this was not sufficiently objective and suggested that we quantify the trails thus leading to the published table. In an attempt to be more analytical we reported the number of sporozoites in the specified number of equivalent fields to at least account for differences in the number of sporozoites for the various groups. We appreciate that our original intent for these data has been validated by Dr. Vanderberg's comment.