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Integrase strand transfer inhibitors (“INSTIs”) are currently in use as a component of prophylactic antiretroviral therapy for preventing HIV-1 infection from progressing to AIDS. Three INSTIs are approved by the FDA for inclusion in antiretroviral regiments: raltegravir (RAL), elvitegravir (EVG) and dolutegravir (DTG). Clinicians have already identified several HIV-1 integrase mutations that confer resistance to RAL and EVG, and additional mutations that confer resistance to all three INSTIs has been identified in the laboratory.

The development of an effective HIV vaccine has been an ongoing area of research. High variability in HIV-1 virus strains, however,  represents a major challenge.  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. Researchers at the National Cancer Institute (NCI) have developed a vaccine that overcomes these major hurdles by utilizing a strategy that identifies conserved regions of the virus and exploits them for use in a targeted therapy.

The baculovirus-based protein expression system has gained increased prominence as a method for expressing recombinant proteins that are used in a wide range of biomedical applications. An important step in the use of this system is the ability to determine the virus infectious titer, i.e., the number of active baculovirus particles produced during an infection of the insect host cell.

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.

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.