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Live-attenuated Rift Valley fever vaccines: comparative mechanisms of trans-placental transmission and vaccine efficacy for developing fetuses

Award Number: R01AI150792
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

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Live-attenuated Rift Valley fever vaccines: comparative mechanisms of trans-placental transmission and vaccine efficacy for developing fetuses - PROJECT SUMMARY/ABSTRACT The World Health Organization warns of a pending public health emergency caused by mosquito-borne zoonotic pathogen Rift Valley fever virus (RVFV). The consequences of this emerging virus could be exacerbated by insufficient vaccines for prevention of infection and disease. RVF is an important agroeconomic illness of domesticated livestock and is endemic in Africa and parts of the Middle East. Further spread is likely given that mosquito species capable of transmitting RVFV are found in Europe and the Americas. The most striking feature of RVF disease in sheep is a wave of fetal loss (known as an “abortion storm”) that sweeps through herds of pregnant animals, where spontaneous abortion rates can reach as high as 90%. Vaccination of livestock protects animals while simultaneously reducing the spread of RVFV to people. Obstacles in the successful development of RVFV livestock vaccines include: 1) vaccine strains often cause fetal infection and death in pregnant animals, and 2) vaccines that protect adult animals from disease are not always effective at preventing vertical transmission during pregnancy. These hurdles represent a major gap in the vaccine development field. The mechanisms by which live-attenuated vaccine strains of RVFV are vertically transmitted in utero, as well as the maternal immune response required for the protection of developing fetuses, are not known. No systematic evaluation of the vertical transmission potential of clinically- relevant live attenuated vaccines has been performed. To address this gap in the field, we propose to use an experimental rodent model of RVFV vertical transmission and fetal death in late-gestation pregnant rats. RVFV directly infects the placenta in rats, causes hemorrhage and inflammation, and results in fetal malformations including intrauterine fetal death even in pregnant dams without signs of disease. This proposal will use the pregnant rat model to test current RVF vaccine candidates for the mechanism(s) of vertical transmission, fetal protection, and identification of maternal immune correlates of fetal protection. We will also conduct a comparative analysis of virulent and attenuated RVFV strains for permissivity of placental explants from relevant species to identify cellular and structural targets of infection. Our overall hypothesis is that infection of pregnant rats with RVFV live-attenuated vaccines will provide pre-clinical quantitative data on vaccine safety for developing fetuses, efficacy for the fetuses, and critical maternal correlates of fetal protection. Completion of these studies will change the paradigm of RVFV vaccine development by providing, for the first time, a mechanistic explanation for the vertical transmission potential of clinically relevant LAVs.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2025 ( Subtotal = $608,641 )
2025	2025	UNIVERSITY OF PITTSBURGH - OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION	4200 FIFTH AVENUE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	5	2/12/2025	NON-COMPETING CONTINUATION	$608,641
														Subtotal = $608,641

Issue Date FY: 2024 ( Subtotal = $634,196 )
2024	2024	UNIVERSITY OF PITTSBURGH - OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION	4200 FIFTH AVENUE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	4	2/16/2024	NON-COMPETING CONTINUATION	$570,777
2024	2024	UNIVERSITY OF PITTSBURGH - OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION	4200 FIFTH AVENUE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	001	4	5/23/2024	NON-COMPETING CONTINUATION	$63,419
														Subtotal = $634,196

Issue Date FY: 2023 ( Subtotal = $632,888 )
2023	2023	UNIVERSITY OF PITTSBURGH - OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION	4200 FIFTH AVENUE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	3	2/24/2023	NON-COMPETING CONTINUATION	$632,888
2023	2022	UNIVERSITY OF PITTSBURGH - OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION	4200 FIFTH AVENUE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	001	2	3/14/2023	SUPPLEMENT FOR EXPANSION	$0
														Subtotal = $632,888

Issue Date FY: 2022 ( Subtotal = $483,301 )
2022	2022	UNIVERSITY OF PITTSBURGH, THE	4200 5TH AVE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	001	2	8/25/2022	SUPPLEMENT FOR EXPANSION	$483,301
2022	2021	UNIVERSITY OF PITTSBURGH, THE	4200 5TH AVE	PITTSBURGH	PA	15260	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	2	4/7/2022	NON-COMPETING CONTINUATION	$0
														Subtotal = $483,301

Issue Date FY: 2021 ( Subtotal = $634,557 )
2021	2021	UNIVERSITY OF PITTSBURGH THE	3520 FIFTH AVE	PITTSBURGH	PA	15213	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	2	2/19/2021	NON-COMPETING CONTINUATION	$634,557
														Subtotal = $634,557

Issue Date FY: 2020 ( Subtotal = $677,858 )
2020	2020	UNIVERSITY OF PITTSBURGH THE	3520 FIFTH AVE	PITTSBURGH	PA	15213	ALLEGHENY	USA	Allergy and Infectious Diseases Research	000	1	2/24/2020	NEW	$677,858
														Subtotal = $677,858

Grand Total All Awards = $3,671,441

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Live-attenuated Rift Valley fever vaccines: comparative mechanisms of trans-placental transmission and vaccine efficacy for developing fetuses

Award Number: R01AI150792

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

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