Genetic Diversity, Evolutionary Dynamics, and Pathogenicity of Ferret Badger Rabies Virus Variants in Mainland China, 2008–2018

Developing a human monoclonal antibody combination CRM25 to prevent rabies after exposure

OBJECTIVE

Immunization against rabies post-exposure prophylaxis requires passive immunization with either monoclonal antibody (mAb) or blood-derived rabies immunoglobin (RIG). Currently, replacing traditional RIG with emerging mAb or mAb combinations is highly recommended due to the limited supply and potential safety risks of RIG.

METHODS

We developed a mAb combination named CRM25 by combining two human mAbs, RM02 and RM05, at a 1:1 mass ratio.

RESULTS

RM02 and RM05 were non-competing and non-overlapping mAbs targeting epitopes I and III, respectively. K226 and G229 were found to be the critical amino acid sites for RM02 neutralization, but the mutant I338T displayed decreased susceptibility to RM05 neutralization. Notably, CRM25 was capable of cross-neutralizing rabies virus (RABV) strains containing K226M or I338T mutations. CRM25 additionally showed an inhibitory effect on the infection of all tested common RABVs and non-RABV phylogroup I lyssaviruses. CRM25 not only exhibited neutralizing activity but also exhibited antiviral effects via Fc-mediated effector functions. Importantly, CRM25 was comparable to human RIG in terms of its capacity to protect Syrian golden hamsters from lethal RABV challenges.

CONCLUSIONS

These findings promote more thorough research on CRM25's antiviral properties in cells and in vivo to enhance its clinical applicability and suggest that it may be a viable candidate medication for rabies post-exposure prophylaxis.

A Global Perspective on Oral Vaccination of Wildlife against Rabies

The long-term mitigation of human-domestic animal-wildlife conflicts is complex and difficult. Over the last 50 yr, the primary biomedical concepts and actualized collaborative global field applications of oral rabies vaccination to wildlife serve as one dramatic example that revolutionized the field of infectious disease management of free-ranging animals. Oral vaccination of wildlife occurred in diverse locales within Africa, Eurasia, the Middle East, and North America. Although rabies is not a candidate for eradication, over a billion doses of vaccine-laden baits distributed strategically by hand, at baiting stations, or via aircraft, resulted in widespread disease prevention, control, or local disease elimination among mesocarnivores. Pure, potent, safe, and efficacious vaccines consisted of either modified-live, highly attenuated, or recombinant viruses contained within attractive, edible baits. Since the late 1970s, major free-ranging target species have included coyotes (Canis latrans), foxes (Urocyon cinereoargenteus; Vulpes vulpes), jackals (Canis aureus; Lupulella mesomelas), raccoons (Procyon lotor), raccoon dogs (Nyctereutes procyonoides), and skunks (Mephitis mephitis). Operational progress has occurred in all but the latter species. Programmatic evaluations of oral rabies vaccination success have included: demonstration of biomarkers incorporated within vaccine-laden baits in target species as representative of bait contact; serological measurement of the induction of specific rabies virus neutralizing antibodies, indicative of an immune response to vaccine; and most importantly, the decreasing detection of rabies virus antigens in the brains of collected animals via enhanced laboratory-based surveillance, as evidence of management impact. Although often conceived mistakenly as a panacea, such cost-effective technology applied to free-ranging wildlife represents a real-world, One Health application benefiting agriculture, conservation biology, and public health. Based upon lessons learned with oral rabies vaccination of mesocarnivores, opportunities for future extension to other taxa and additional diseases will have far-reaching, transdisciplinary benefits.

Molecular analysis and geographic distribution of the recent Indonesian rabies virus

Background and Aim

Some Indonesian islands, including Sumatra, Kalimantan, Sulawesi, Java, and East Nusa Tenggara, have endemic rabies. Rabies outbreaks in Bali began from 2008 to 2011 and continue to occur sporadically. This study aimed to study the molecular analysis and geographical distribution of Indonesian rabies virus (RABV) from 2016 to 2021 and compare to previous periods.

Materials and Methods

Virus isolates from 2016 to 2021 were extracted from dog brains and sequenced at the nucleoprotein gene locus. They were compared with data sequences available in the GenBank database. Indonesian RABV from the previous three periods (before 1989, 1997-2003, and 2008-2010) was extracted from the GenBank database. The genetic diversity in this study was based on the N gene of Indonesian RABV.

Results

Asian RABV, which is genetically close to the Indonesian virus, is a virus from China (ASIA-3 cluster) and from the Southeast Asia region, namely, virus isolates from Sarawak and Malaysia and some Cambodian isolates. Rabies virus, which was isolated from the Bali islands, was the new cluster first detected and published in Bali, Indonesia, in 2008, while RABV from West Sumatra Province, which was isolated from 2016 to 2021, was also considered a new cluster that is genetically distant from other clusters in Indonesia.

Conclusion

The RABV in Indonesia is divided into five clusters. The isolates from West Sumatra Province from 2016 to 2021 were a new cluster genetically distant from other Indonesian viruses.