Development and preclinical evaluation of a new F(ab')2 antitoxin against botulinum neurotoxin serotype A.

Concern about the malicious applications of botulinum neurotoxin has highlighted the need for a new generation of safe and highly potent antitoxins. In this study, we developed and evaluated the preclinical pharmacology and safety of a new F(ab')2 antitoxin against botulinum neurotoxin serotype A (BoNT/A). As an alternative to formalin-inactivated toxoid, the recombinant Hc domain of botulinum neurotoxin serotype A (rAHc) was used to immunize horses, and the IgGs from the hyperimmune sera were digested to obtain F(ab')2 antitoxin. The protective effect of the new F(ab')2 antitoxin against BoNT/A was determined both in vitro and in vivo. The results showed that the F(ab')2 antitoxin could prevent botulism in mice challenged with BoNT/A and effectively delayed progression of paralysis from botulism in the therapeutic setting. The preclinical safety of the new F(ab')2 antitoxin was also evaluated, and it showed neither harmful effects on vital functions nor adverse effects such as acute toxicity, or immunological reactions in mice and dogs. Thus, our results provide valuable experimental data for this new antitoxin as a potential candidate for treatment of botulism caused by BoNT/A, and our findings support the safety of the new F(ab')2 antitoxin for clinical use. Our study further demonstrates the proof of concept for development of a similar strategy for obtaining potent antitoxin against other BoNT serotypes.

EGCG mitigates neurotoxicity mediated by HIV-1 proteins gp120 and Tat in the presence of IFN-gamma: role of JAK/STAT1 signaling and implications for HIV-associated dementia.

Human immunodeficiency virus (HIV)-1 infection of the central nervous system occurs in the vast majority of HIV-infected patients. HIV-associated dementia (HAD) represents the most severe form of HIV-related neuropsychiatric impairment and is associated with neuropathology involving HIV proteins and activation of proinflammatory cytokine circuits. Interferon-gamma (IFN-gamma) activates the JAK/STAT1 pathway, a key regulator of inflammatory and apoptotic signaling, and is elevated in HIV-1-infected brains progressing to HAD. Recent reports suggest green tea-derived (-)-epigallocatechin-3-gallate (EGCG) can attenuate neuronal damage mediated by this pathway in conditions such as brain ischemia. In order to investigate the therapeutic potential of EGCG to mitigate the neuronal damage characteristic of HAD, IFN-gamma was evaluated for its ability to enhance well-known neurotoxic properties of HIV-1 proteins gp120 and Tat in primary neurons and mice. Indeed, IFN-gamma enhanced the neurotoxicity of gp120 and Tat via increased JAK/STAT signaling. Additionally, primary neurons pretreated with a JAK1 inhibitor, or those derived from STAT1-deficient mice, were largely resistant to the IFN-gamma-enhanced neurotoxicity of gp120 and Tat. Moreover, EGCG treatment of primary neurons from normal mice reduced IFN-gamma-enhanced neurotoxicity of gp120 and Tat by inhibiting JAK/STAT1 pathway activation. EGCG was also found to mitigate the neurotoxic properties of HIV-1 proteins in the presence of IFN-gamma in vivo. Taken together, these data suggest EGCG attenuates the neurotoxicity of IFN-gamma augmented neuronal damage from HIV-1 proteins gp120 and Tat both in vitro and in vivo. Thus EGCG may represent a novel natural copound for the prevention and treatment of HAD.

[The mouse paw edema test for titrating Shigella toxin and antitoxin and for determining the safety of the anatoxin]. / Test oteka lapy myshi dlia titrovaniia shigelleznogo toksina, antitoksina i opredeleniia bezvrednosti anatoksina.

The method for the titration of Shigella dysenteriae I neurotoxin, toxoid prepared from this toxin and different antitoxic preparations in the mouse paw edema test has been developed. The quantitative determination of antitoxin is based on the neutralization test. The conditions of titration (the dilutions of the neurotoxin and the neutralization doses of the antitoxin), as well as criteria for the evaluation of the positive or negative results, have been established.