Immune Response to Arthropod Blood Feeding (R21 Clinical Trial Not Allowed) | PAR 18 860

Opportunity Information: Apply for PAR 18 860

The National Institutes of Health (NIH) funding opportunity titled "Immune Response to Arthropod Blood Feeding (R21 Clinical Trial Not Allowed)" (Funding Opportunity Number PAR 18 860; CFDA 93.855) is a discretionary grant program designed to support short-term, exploratory, and developmental research on what happens immunologically when blood-feeding arthropods bite and feed. Using the NIH R21 mechanism, the announcement emphasizes early-stage, high-impact studies that can open up new lines of inquiry, encourage transdisciplinary collaborations, and generate foundational data in an area that connects immunology, vector biology, and host-pathogen interactions. As indicated by the title, clinical trials are not allowed under this FOA, so proposed work should be preclinical, mechanistic, or otherwise non-clinical in nature.

The core scientific focus is on the immune events triggered by hematophagous arthropods during and after a blood meal. A central objective is to understand immune responses in the vertebrate host both locally and systemically. Locally, the FOA highlights the bite site in the skin, where the earliest interactions occur between arthropod salivary factors, tissue-resident immune cells, and recruited inflammatory cells. Systemically, it encourages research into how the initial skin-level response may cascade into broader immune changes throughout the body, potentially shaping susceptibility to infection, inflammatory outcomes, or longer-term immune memory related to repeated exposures. This framing supports projects that look at immediate innate responses, downstream adaptive responses, and the timing and signaling pathways that connect events at the skin to immune activity in distant tissues.

A second major objective is to identify and characterize immune-modulatory properties of arthropod salivary components. Many blood-feeding arthropods inject saliva that contains pharmacologically active molecules that help them feed by reducing pain, limiting blood clotting, and dampening host inflammation. This FOA is interested in how those salivary molecules actively reshape host immunity, including which specific salivary proteins, peptides, lipids, or other factors are responsible, what host receptors and pathways they engage, and what immunologic outcomes they produce. Research responsive to this objective could include work that isolates salivary factors, maps their bioactivity, connects them to changes in cytokine profiles or antigen presentation, or explains how saliva alters cellular recruitment and function at the feeding lesion. The broader implication is that understanding these salivary immune effects may clarify why vector-borne pathogens transmit efficiently, why some bites lead to exaggerated reactions, and how repeated exposure alters immune responsiveness.

The third scientific objective turns attention to the arthropods themselves, specifically the immunological events occurring in hematophagous arthropods following a blood meal. Blood feeding is not only a challenge for the host; it also creates major physiological and immune pressures for the arthropod, influencing gut immunity, microbial dynamics, and the arthropod's ability to support or restrict pathogen replication. This FOA therefore supports projects that examine arthropod immune pathways activated by the blood meal, changes in gene expression or immune effector production, and how these processes might affect vector competence. By including this objective, the program encourages bidirectional thinking: the bite is a two-organism immunological event, and host and vector responses can influence one another in ways that affect disease transmission.

In terms of applicant eligibility, the program is broadly open to many organization types. Eligible applicants include state, county, city or township, and special district governments; independent school districts; public and state-controlled institutions of higher education; private institutions of higher education; federally recognized Native American tribal governments; Native American tribal organizations that are not federally recognized governments; public housing authorities and Indian housing authorities; nonprofit organizations with or without 501(c)(3) status (excluding institutions of higher education in those categories as specified); for-profit organizations other than small businesses; and small businesses. The FOA also explicitly calls out additional eligible applicant categories such as Historically Black Colleges and Universities (HBCUs), Hispanic-serving Institutions, Tribally Controlled Colleges and Universities (TCCUs), Alaska Native and Native Hawaiian Serving Institutions, and Asian American Native American Pacific Islander Serving Institutions (AANAPISIs), as well as faith-based or community-based organizations, regional organizations, eligible federal agencies, non-U.S. entities (foreign organizations), and U.S. territories or possessions. This wide eligibility language reflects NIH's interest in attracting diverse scientific perspectives and institutional capacities, including global expertise relevant to arthropod exposure and vector-borne disease ecology.

Administratively, the opportunity is offered as a grant under the health funding activity category. The source information lists an award ceiling of $200,000, and the opportunity was created on July 19, 2018. The original closing date shown is October 15, 2020. Overall, the announcement is best understood as an NIH effort to seed innovative mechanistic research that clarifies how blood-feeding arthropods and their salivary factors shape immunity in the host and within the vector, with the long-term aim of improving the scientific foundation for interventions that may eventually reduce bite-associated pathology or interrupt transmission of vector-borne pathogens, while staying firmly outside the scope of clinical trial work.

• The National Institutes of Health in the health sector is offering a public funding opportunity titled "Immune Response to Arthropod Blood Feeding (R21 Clinical Trial Not Allowed)" and is now available to receive applicants.
• Interested and eligible applicants and submit their applications by referencing the CFDA number(s): 93.855.
• This funding opportunity was created on 2018-07-19.
• Applicants must submit their applications by 2020-10-15. (Agency may still review applications by suitable applicants for the remaining/unused allocated funding in 2026.)
• Each selected applicant is eligible to receive up to $200,000.00 in funding.
• Eligible applicants include: State governments, County governments, City or township governments, Special district governments, Independent school districts, Public and State controlled institutions of higher education, Native American tribal governments (Federally recognized), Public housing authorities/Indian housing authorities, Native American tribal organizations (other than Federally recognized tribal governments), Nonprofits having a 501 (c) (3) status with the IRS, other than institutions of higher education, Nonprofits that do not have a 501 (c) (3) status with the IRS, other than institutions of higher education, Private institutions of higher education, For-profit organizations other than small businesses, Small businesses, Others.

Apply for PAR 18 860

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