Soluble forms (sCD4) of human CD4, the HIV-1 primary receptor, are potent HIV-1 entry inhibitors. Both four-domain (D1-4) and two-domain (D1D2) sCD4 and their fusion proteins have been tested as candidate therapeutics in animal models and in human clinical trials and were well tolerated by patients with no significant clinical or immunologic toxicities and exhibited significant inhibitory activities. However, their activities were transient and the virus rapidly rebound.

Soluble forms of human CD4 (sCD4) inhibit HIV-1 entry into immune cells.  Different forms of sCD4 and their fusion proteins have been extensively studied in animal models and clinical trials as promising HIV-1 inhibitors. However, they have not been successful in clinical trials due to their transient efficacy.  sCD4 is also known to interact with class II major histocompatibility complex (MHCII) and, at low concentrations, could enhance HIV-1 infectivity. 

The development of an effective HIV vaccine has been an ongoing area of research. The high variability in HIV-1 virus strains has represented a major challenge in successful development.  Ideally, an effective candidate vaccine would provide protection against the majority of clades of HIV.  Two major hurdles to overcome are immunodominance and sequence diversity.  This vaccine utilizes a strategy for overcoming these two issues by identifying the conserved regions of the virus and exploiting them for use in a targeted therapy. 

No effective therapeutics or vaccines against Middle East Respiratory Syndrome Coronavirus (MERS-CoV) are available. The human-to-human aspect of transmission and the high mortality rate associated with MERS-CoV infection have raised concerns over the potential for a future MERS-CoV pandemic and emphasized the need for development of effective therapeutics and vaccines.

Scientists at NIAID have developed two immortalized stable B cell lines from rhesus macaques that can have value as research tools for the discovery of neutralizing antibodies of simian origin against HIV and that may have value in the development of an HIV vaccine. These B cell lines encode human Bcl-6 and Bcl-xL proteins, which are major regulators of apoptosis. These B cell lines are derived from the lymph node of a rhesus macaque (RM) that was infected with SHIV.CH505.

Despite four decades of intensive research, a safe and effective HIV-1 vaccine remains elusive due to the extreme difficulty in eliciting broadly neutralizing antibodies (bNAbs), which recognize and block HIV-1 from entering healthy cells. Only rare natural HIV-1 envelopes (Envs) promote the activation and expansion of naive B cells expressing unmutated germline antibodies of various bNAb lineages, but they typically do so for a single lineage for the same neutralization site.

NIAID scientists have developed plasmids that allow for production of pseudoviruses expressing SARS-CoV-2 spike protein. As SARS-CoV-2 is a lethal airborne virus, it must be handled in high-containment Biosafety Level 3 (BSL-3) laboratories that require strict airflow, ventilation and decontamination procedures.

The emergence of the SARS-CoV-2 virus and its immune-escaping variants have led to global COVID-19 pandemic/endemic, underscoring the urgent need for effective vaccines with strong and durable immune responses.