Pan-African polyspecific antivenom produced by caprylic acid purification of horse IgG: an alternative to the antivenom crisis in Africa

Abstract

A polyspecific Pan-African antivenom has been produced from the plasma of horses immunized with a mixture of the venoms of Echis ocellatus, Bitis arietans and Naja nigricollis, the three most medically important snakes in sub-Saharan Africa. The antivenom is a whole IgG preparation, obtained by caprylic acid precipitation of non-IgG plasma proteins. The antivenom effectively neutralizes the most important toxic activities of the three venoms used in the immunization in standard assays involving preincubation of venom and antivenom before testing. This antivenom compares favourably with other antivenoms designed for use in Africa with respect to neutralization of the toxins present in the venom of E. ocellatus. Caprylic acid fractionation of horse hyperimmune plasma is a simple, convenient and cheap protocol for the manufacture of high quality whole IgG antivenoms. It constitutes a potentially valuable technology for the alleviation of the critical shortage of antivenom in Africa.

Antivenomic Assessment of the Immunological Reactivity of EchiTAb-Plus-ICP, an Antivenom for the Treatment of Snakebite Envenoming in Sub-Saharan Africa

“…51 Bleeding and coagulopathy are the most important systemic pathophysiological manifestations of these envenomings, creating the risk of provoking hemorrhagic strokes, haemodynamic disturbances, cardiovascular collapse, and disseminated intravascular coagulation. 4 Thus, the effective immunodepletion of SVMPs and serine proteinases by the EchiTAb-Plus-ICP antivenom correlates well with our earlier reports of the preclinical venom-neutralizing effectiveness of this antivenom against these important African vipers (using assays of venom-induced lethality, hemorrhage, and coagulation 19,20 and its clinical efficacy in treating human victims of E. ocellatus envenoming. 27 The partial immunological reactivity to some PLA 2 s, disintegrins, and proteinase inhibitors revealed the presence of low affinity or low abundance of antibodies against these components in the antivenom.…”

“…However, keep in mind that immunodepletion does not necessarily imply therapeutic neutralization of these venoms and, therefore, antivenomic analysis has to be complemented by preclinical neutralization studies, followed by appropriate clinical trials. In this respect, preclinical studies with the venoms analyzed in this work performed with EchiTAb-Plus-ICP , 20 showed that this antivenom neutralizes the most clinically relevant toxic (lethal, hemorrhagic, coagulant, and necrotizing) activities of these venoms, 19,20 and also of the venoms of other medically important sub-Saharan African species, i.e., E. leucogaster , E. pyramidum leakeyi , B. gabonica , B. rhinoceros , and B. nasicornis . 20 We conclude, therefore, that partially immunodepleted toxins may not compromise the in vivo neutralizing efficacy of EchiTAb-Plus-ICP antivenom.…”

“…6,7,11,14,15 Several manufacturers have responded developing antivenoms for sub-Saharan Africa. Thus, in addition to laboratories traditionally producing antivenoms for Africa, such as EgyVac (Egypt), Sanofi-Pasteur (France), and South African Vaccine Producers (South Africa), 16 other manufacturers have recently developed new antivenoms for this region, e.g., MicroPharm (UK), 17 Instituto Bioclon (Mexico), 11,18 Instituto Clodomiro Picado (Costa Rica), 19,20 and Instituto Butantan (Brazil) (Diasda-Silva W, personal communication). However, there was a large heterogeneity in the design and composition of the venoms used in the immunization mixtures to prepare the above antivenoms, an issue complicated by the complexity of subSaharan herpetofauna and by the diversity of African snake venom proteomes ("venoms"), including intraspecies venom variability in those species with a wide geographical distribution.…”

“…7,[23][24][25][26] In the case of viperid snake venoms, which inflict the highest toll of envenoming in sub-Saharan Africa, 4 preclinical analysis of the neutralizing efficacy of antivenoms should include the neutralization of lethal, hemorrhagic, coagulant, defibrinogenating, and necrotising effects. In the case of EchiTAb-Plus-ICP antivenom, produced by immunizing horses with a mixture of the venoms of Echis ocellatus , Bitis arietans , and Naja nigricollis from Nigeria, 19,20 preclinical analyses have already showed its effectiveness in the neutralization not only of these three venoms, 19 but also of the venoms of other Echis saw-scaled viper species ( Echis leucogaster , Echis pyramidum leakeyi ) and other Bitis viper species ( Bitis gabonica , Bitis rhinoceros , and Bitis nasicornis ). 20 Moreover, this antivenom proved clinically effective and safe in a powerful trial performed in Nigeria in patients systemically envenomed by E. ocellatus.…”

“…The polyspecific EchisTAb-Plus-ICP antivenom was manufactured by caprylic acid fractionation of the plasma of four horses that had been immunized with a mixture (at a weight ratio of 1:1:1.33) of the venoms of Echis ocellatus , Bitis arietans , and Naja nigricollis collected from Nigeria. 19 The particular antivenom batch used in this preclinical study (Batch 4260308PALQ) was formulated to have the following composition: protein concentration 69.6 g/L, sodium chloride 7.6 g/L, phenol 1.86 g/L, and pH 6.78. The antivenom batch passed all the quality control requirements at the Quality Control Laboratory of Instituto Clodomiro Picado.…”