Exceptionally Potent Cross-Reactive Neutralization of Nipah and Hendra Viruses by a Human Monoclonal Antibody

Self Cite

Soluble forms of the human immunodeficiency virus type 1 (HIV-1) primary receptor CD4 (soluble CD4 [sCD4]) have been extensively characterized for a quarter of a century as promising HIV-1 inhibitors, but they have not been clinically successful. By combining a protein cavity-filling strategy and the power of library technology, we identified an engineered cavity-altered single-domain sCD4 (mD1.22) with a unique combination of excellent properties, including broad and potent neutralizing activity, high specificity, stability, solubility, and affinity for the HIV-1 envelope glycoprotein gp120, and small molecular size. To further improve its neutralizing potency and breadth, we generated bispecific multivalent fusion proteins of mD1.22 with another potent HIV-1 inhibitor, an antibody domain (m36.4) that targets the coreceptor-binding site on gp120. The fusion proteins neutralized all HIV-1 isolates tested, with potencies about 10-, 50-, and 200-fold higher than those of the broadly neutralizing antibody VRC01, the U.S. FDA-approved peptide inhibitor T20, and the clinically tested sCD4-Fc fusion protein CD4-Ig, respectively. In addition, they exhibited higher stability and specificity and a lower aggregation propensity than CD4-Ig. Therefore, mD1.22 and related fusion proteins could be useful for HIV-1 prevention and therapy, including eradication of the virus. Soluble forms of human CD4 (sCD4) comprising all four (D1 to D4) or the first two (D1D2) extracellular domains are potent inhibitors of the human immunodeficiency virus type 1 (HIV-1) in vitro (1, 2). Several promising monomeric (3-5), dimeric (6-8), and tetrameric (9-11) sCD4 derivatives have been tested in animal models and in human clinical trials, but they exhibited modest and transient antiviral activities. Previously, we demonstrated that decreasing the molecular size of D1D2 to a single domain, D1, significantly increased its antiviral activity and reduce its nonspecificity, i.e., interactions with molecules other than the HIV-1 envelope glycoprotein (Env) gp120; a D1 variant (mD1.2) was identified that is also more soluble than D1D2 (12). However, mD1.2 still binds to human B cells and CD4 ϩ T cells without HIV-1 Env expression, although it binds more weakly than D1D2 and its stability is comparable to that of D1D2, which is relatively low (12).It has been shown previously that some proteins exhibit poor hydrophobic packing, leading to low stability and solubility due to the presence of cavities within or on the surfaces of proteins that are either empty or hydrated (13,14). Identification of such cavities and filling them with bulkier hydrophobic amino acid side chains have proven effective in improving stability and other properties of proteins (15). By combining this cavity-filling strategy with the power of library technology, we identified an mD1.2 mutant, designated mD1.22, that has significantly higher soluble expression, thermal stability, and specificity than mD1.2. Bispecific multivalent fusion proteins of mD1.22 with m36.4, an engineered ...

“…3). m102.4, a negative-control antibody specific to Nipah and Hendra viruses (19), did not significantly inhibit any isolate tested.…”

Section: Resultsmentioning

confidence: 89%

mentioning

confidence: 99%

Exceptionally Potent and Broadly Cross-Reactive, Bispecific Multivalent HIV-1 Inhibitors Based on Single Human CD4 and Antibody Domains

Chen

Yang

Prabakaran

et al. 2014

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“…This transport might be additionally inhibited by the lower Fc-Fc receptor interactions between mouse MAbs and the ferret host. In addition, the half-life of mouse IgG in ferrets has not been well characterized; however, a previous study that examined the therapeutic potential of a humanized MAb, m102, in the ferret model of Nipah virus infection reported an elimination half-life of 3.5 days following the intravenous administration of 25 mg of MAb (50). We were therefore curious if treatment with a large dose of MAb (30 mg/kg) would increase the Ab concentration on mucosal surfaces and protect from upper respiratory tract infection.…”

Section: Resultsmentioning

confidence: 99%

Assessment of Influenza Virus Hemagglutinin Stalk-Based Immunity in Ferrets

Krammer

Hai

Yondola

et al. 2014

128

131

Therapeutic monoclonal antibodies that target the conserved stalk domain of the influenza virus hemagglutinin and stalk-based universal influenza virus vaccine strategies are being developed as promising countermeasures for influenza virus infections. The pan-H1-reactive monoclonal antibody 6F12 has been extensively characterized and shows broad efficacy against divergent H1N1 strains in the mouse model. Here we demonstrate its efficacy against a pandemic H1N1 challenge virus in the ferret model of influenza disease. Furthermore, we recently developed a universal influenza virus vaccine strategy based on chimeric hemagglutinin constructs that focuses the immune response on the conserved stalk domain of the hemagglutinin. Here we set out to test this vaccination strategy in the ferret model. Both strategies, pretreatment of animals with a stalk-reactive monoclonal antibody and vaccination with chimeric hemagglutinin-based constructs, were able to significantly reduce viral titers in nasal turbinates, lungs, and olfactory bulbs. In addition, vaccinated animals also showed reduced nasal wash viral titers. In summary, both strategies showed efficacy in reducing viral loads after an influenza virus challenge in the ferret model. IMPORTANCEInfluenza virus hemagglutinin stalk-reactive antibodies tend to be less potent yet are more broadly reactive and can neutralize seasonal and pandemic influenza virus strains. The ferret model was used to assess the potential of hemagglutinin stalk-based immunity to provide protection against influenza virus infection. The novelty and significance of the findings described in this report support the development of vaccines stimulating stalk-specific antibody responses.

“…While there are currently no approved treatments, several treatment and vaccine candidates have been evaluated using rodent, cat, and ferret models. The most successful treatment strategy reported to date makes use of the cross-neutralizing, fully human monoclonal antibody m102.4 (5,30). This passive antibody treatment proved fully protective when a single dose was administered 10 h postchallenge in a ferret model of lethal NiV infection.…”

Section: Discussionmentioning

confidence: 99%

A Novel Model of Lethal Hendra Virus Infection in African Green Monkeys and the Effectiveness of Ribavirin Treatment

Rockx¹,

Bossart

Feldmann³

et al. 2010

110

121

The henipaviruses, Hendra virus (HeV) and Nipah virus (NiV), are emerging zoonotic paramyxoviruses that can cause severe and often lethal neurologic and/or respiratory disease in a wide variety of mammalian hosts, including humans. There are presently no licensed vaccines or treatment options approved for human or veterinarian use. Guinea pigs, hamsters, cats, and ferrets, have been evaluated as animal models of human HeV infection, but studies in nonhuman primates (NHP) have not been reported, and the development and approval of any vaccine or antiviral for human use will likely require efficacy studies in an NHP model. Here, we examined the pathogenesis of HeV in the African green monkey (AGM) following intratracheal inoculation. Exposure of AGMs to HeV produced a uniformly lethal infection, and the observed clinical signs and pathology were highly consistent with HeV-mediated disease seen in humans. Ribavirin has been used to treat patients infected with either HeV or NiV; however, its utility in improving outcome remains, at best, uncertain. We examined the antiviral effect of ribavirin in a cohort of nine AGMs before or after exposure to HeV. Ribavirin treatment delayed disease onset by 1 to 2 days, with no significant benefit for disease progression and outcome. Together our findings introduce a new disease model of acute HeV infection suitable for testing antiviral strategies and also demonstrate that, while ribavirin may have some antiviral activity against the henipaviruses, its use as an effective standalone therapy for HeV infection is questionable.