FDA Grant for Identifying Target Peptide Sequences for Zika IgM Diagnostic Device Development

This research funding opportunity is to propose developing diagnostic tools to obtain an accurate diagnosis of infection with Zika virus, an initiative that is particularly important for pregnant women. Since the Zika virus usually remains in the blood of an infected person for about seven days, nucleic acid-based (RT-PCR) tests will not detect Zika virus RNA in an infected person, or a newborn who had Zika virus infection in utero, after the period of viremia has passed. Thus, nucleic acid tests will not be very effective in diagnosing Zika infection. Serologic tests for IgM are likely to be more useful than RT-PCR for diagnosis of Zika infection; however, the current tests for Zika virus IgM are often falsely positive because of cross-reacting IgM antibodies against related flaviviruses (e.g., Dengue, West Nile, and Yellow Fever viruses). Consequently, a positive result for Zika IgM requires additional testing to confirm the initial positive result. Development of serology assays with high sensitivity and specificity are thus a critical need. The selected Source should propose approaches to identify specific peptides from Zika virus that will enable the detection of IgM antibodies against Zika virus without the requirement for additional testing. The ultimately selected approach should use well established technology and hence has a high probability of success.

BACKGROUND
The proposed funded research plan should have a high probability of success in large part due to the broad experience and track record of personnel with expertise in the established proposed technology.

The recommended technical approach will be to use peptide microarrays to identify specific Zika virus peptides for use in serological diagnostic assays. A peptide microarray (also commonly known as peptide chip or peptide epitope microarray) is a collection of peptides displayed on a solid surface, usually a glass or plastic chip. The peptide microarray is a well-established technology used successfully in a variety of studies similar to current effort, as described in detail below.

Peptide chips are used to study binding properties and kinetics of protein-protein interactions. In basic research, peptide microarrays are often used to profile an enzyme, to map an antibody epitope or to find key residues for protein binding. Practical applications are seromarker discovery, profiling of changing humoral immune responses of individual patients during disease progression, monitoring of therapeutic interventions, patient stratification and development of diagnostic tools and vaccines.

Some studies that exemplify the use of this technology include epitope analysis after immune activation, identification of new diagnostic biomarkers of human typhoid by immune profiling, or vaccine development by studying the presence of 44 conserved peptides between dengue virus 1 – 4 that could be used as a target for vaccination. Kahn et al., 2008 showed that some, but not all, conserved dengue peptides are shared with other viruses like Zika. This illustrates the possibility of finding some peptides that are Zika specific. To date, there has not been an epitope map produced to identify the strongest immunogens in the Zika proteome; this void can be filled by the use of peptide microarray technology. This epitope discovery should be the objective of the proposed funded research.

REGULATORY IMPACT
The peptide information generated by this proposed funded research will allow the FDA to identify differential peptides that will be used in serological assays to diagnose Zika virus infection without the requirement for burdensome confirmation of positive results. The knowledge obtained by this study will be made available either by the FDA web site or by a peer-reviewed scientific publication. Any interested company or public health institution will be able to use the published results for the design and/or evaluation of targeted diagnostic applications. This will represent a significant advance for the Medical Counter Measure community by enhancing the ability to quickly and easily identify an emerging pathogen from a set of commonly cross-reactive flaviviruses.

Studies, such as this proposed funded research, are needed to guide the design of Zika virus diagnostics that are currently unavailable and in urgent need. Early and correct diagnosis of Zika virus infection in pregnant women is critically important to identify babies with a potential risk of microcephaly. Microcephaly is diagnosed when an infant’s head is smaller than expected as compared to infants of the same age and sex. Problems from microencephaly can range from mild to severe, are often life-long, and in some cases can be life-threatening.

There is a critical gap in the diagnostic tools available for Zika virus; this gap severely impacts FDA’s and other public health institutions overall readiness to respond to Arbovirus outbreaks, consequently endangering the public health. Without this critical study, the ability to identify Zika virus infections accurately will continue to be severely hampered by cross-reacting flaviviruses such as Dengue, West Nile and Yellow Fever.

Specifics:
Approximately 10 (ten) viral Zika samples are needed. Viruses from potential co-infection need to be represented as well and FDA recommends analysis of 10 (ten) Dengue 1-4, 10 (ten) Yellow Fever, 10 (ten) West Nile, 10 (ten) Chikungunya, and 2 (two) uninfected samples from collaborators.