# A Sphingomyelin Hydrolase Regulates the Late Stages of HIV Assembly and Budding

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2022 · $590,643

## Abstract

ABSTRACT
HIV assembly occurs at the plasma membrane within specialized membrane microdomains (commonly known
as lipid rats) that exhibit reduced lateral mobility owing to an enrichment of saturated lipids including PIP2,
ceramide, sphingomyelin, and sterols. The HIV-1 Gag precursor protein targets to the inner leaflet of these
plasma membrane microdomains and regulates essential events required for virion assembly and budding.
However, the mechanisms by which Gag regulates the formation of these microdomains and the role for these
microdomains in viral assembly is currently unknown. Here we provide the first evidence that Gag co-localizes
with the sphingomyelin hydrolase nSMase2 (which catalyzes the formation of ceramide from sphingomyelin),
and that nSMase2 is a critical regulator of HIV replication. In preliminary experiments we discovered that this
enzyme is required for the successful completion of the late stages of HIV assembly and maturation.
Pharmacological inhibition or genetic deletion of nSMase2 prevented the processing of Gag and resulted in the
production of irregularly shaped immature non-infectious virions. In humanized HIV infected mice, inhibition of
nSMase2 produced a linear decrease of viral loads to below detectable limits in the majority of animals tested.
More importantly, animals who achieved viral loads below detectable limits with treatment, did not exhibit viral
rebound when drug administration was discontinued. The findings from these studies will increase our basic
understanding of the viral replication cycle by describing for the first time a role for nSMase2 and ceramide in
HIV replication.

## Key facts

- **NIH application ID:** 10548445
- **Project number:** 1R01MH131469-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Norman J Haughey
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $590,643
- **Award type:** 1
- **Project period:** 2022-07-15 → 2027-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10548445

## Citation

> US National Institutes of Health, RePORTER application 10548445, A Sphingomyelin Hydrolase Regulates the Late Stages of HIV Assembly and Budding (1R01MH131469-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10548445. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*