Zika Virus Peptides Identification in Saliva After 9-months Infection

Objectives: To demonstrate the applicability of a mass spectrometry-based proteomic technique for identification of Zika virus (ZIKV) peptides in saliva of patients previously diagnosed with ZIKV.
Methods: A 25-year old woman clinically diagnosed with ZIKV infection in the first trimester gave birth to dizygotic twins, baby-A (female) had microcephaly while the baby-B (male) did not have microcephaly. Saliva was collected from mother and babies 3 months after birth (a total of 9-months post ZIKV infection). Peptidomic analysis was completed by mass spectrometry. MS/MS data was searched against a specific ZIKV protein database. Identified ZIKV peptides were aligned/mapped to the ZIKV polyprotein regions. Lastly, phylogenetic analyses were generated from the peptidomic data.
Results: We could identify ZIKV peptides in saliva 9 months after infection. A total of 420 (mother), 670 (baby-A), and 183 (baby-B) ZIKV peptides were identified in saliva, which covered 67% (mother), 84% (baby A), and 45% (baby-B) of the ZIKV polyprotein. A significant shift was noted in the number of amino acid residues per peptide on baby-A (female affected by microcephaly) when compared to mother and baby-B (male not affected by microcephaly). Additionally, both mother and baby A demonstrated similar structural/non-structural ratio, whereas baby B showed a slightly reduced ratio of structural peptides.
Conclusions: Timely diagnosis of ZIKV infection can allow us to act decisively and take preventative measures in terms of containing the spread of Zika virus infection. Thus, we introduce an innovative approach to assessing the presence of ZIKV peptides in saliva. Moreover, our data strongly confirms a vertical transmission (mother to babies). We can definitively conclude that our novel approach of looking at natural occurring peptides from ZIKV increases the window of detection when compared to RNA-based diagnostics.