Human Antibody Response to Aedes aegypti Mosquitoes Aids in Determining Effectiveness of Vector-control Methods

As arboviruses such as Zika, Dengue, and Chikungunya continue to plague regions around the world, researchers have been working hard to create vaccines to treat these infections. In the absence of these immunizations, however, vector-control methods are still the number one way to protect individuals from infection. As such, tests to determine human exposure to these viruses before and after vector-control methods will aid in determining the effectiveness of such methods.

Past studies have described a biomarker in the form of the human antibody (Ab) response to Aedes aegypti Nterm-34kDa salivary peptide that identifies human contact with this vector that also transmits the devastating arboviruses. A new study published in PLOS Neglected Tropical Diseases sought to determine if this biomarker could also be used to estimate the effectiveness of vector-control efforts.

The researcher's test measured the presence of human IgG antibodies that react to the Aedes salivary protein, the Nterm-34kDa peptide both before and after vector-control methods were implemented. Blood samples were tested for the presence of the antibodies in the blood of 102 individuals between the ages of 18 and 65 from Saint-Denis, La Reunion Island in the Indian Ocean, before and 15, 30, and 45 days after vector-control measures were implemented. (The study defined vector control measures as “i) physical elimination of Aedes positive breeding sites combined with ii) spatial spraying of deltamethrin insecticide at 1g/ha concentration, twice two days apart, as previously described.”) The team also questioned the subjects regarding any personal measures taken to reduce the risk of exposure to the vector.

The authors found that approximately 88% of the participants reacted to the Nterm-34kDa peptide prior to the implementation of vector-control measures at a rate that was higher than the cut off. The authors determined that this exceptionally high response rate was indicative of the effectiveness of the test. They wrote, “The usefulness of measuring a human antibody response against Ae. albopictus using the Nterm-34kDa peptide was validated in individuals that were exposed to the bites of Ae. albopictus and individuals that were not exposed.”

When blood samples were collected again after 30 days of vector-control measures, the exposure rate dropped to 67.64% among the same subject group. The authors noted “no significant difference was observed between” day 30 and day 45 after vector-control measures were implemented.

Based on these results, the authors concluded that the results of their study, “show[ed] that the level of specific [human antibody] response and the proportion of immune responders significantly decreased after [vector control implementation].” Arguably ,the results of this study add to the evidence that vector-control methods are effective in curbing exposure to tropical diseases such as the Zika virus.