The incurable wound revisited: progress in human rabies prevention?

Preclinical animal models to evaluate therapeutic antiviral antibodies

Despite the availability of effective preventative vaccines and potent small-molecule antiviral drugs, effective non-toxic prophylactic and therapeutic measures are still lacking for many viruses. The use of monoclonal and polyclonal antibodies in an antiviral context could fill this gap and provide effective virus-specific medical interventions. In order to develop these therapeutic antibodies, preclinical animal models are of utmost importance. Due to the variability in viral pathogenesis, immunity and overall characteristics, the most representative animal model for human viral infection differs between virus species. Therefore, throughout the years researchers sought to find the ideal preclinical animal model for each virus. The most used animal models in preclinical research include rodents (mice, ferrets, …) and non-human primates (macaques, chimpanzee, ….). Currently, antibodies are tested for antiviral efficacy against a variety of viruses including different hepatitis viruses, human immunodeficiency virus (HIV), influenza viruses, respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and rabies virus. This review provides an overview of the current knowledge about the preclinical animal models that are used for the evaluation of therapeutic antibodies for the abovementioned viruses.

Time to Revise the WHO Categories for Severe Rabies Virus Exposures–Category IV?

Rabies is a devastating disease and affects millions of people globally, yet it is preventable with appropriate and timely postexposure prophylaxis (PEP). The current WHO exposure categories (Categories I, II, and III) need revision, with a special Category IV for severe exposures. Rare cases of PEP failure have occurred in severe bites to the head and neck. Multiple factors, including route, wound severity, depth, contamination, viral dose, proximity to highly innervated areas and the CNS, and the number of lesions, remain unconsidered. Injuries in areas of high neural density are the most significant considering lyssavirus pathophysiology. Current recommendations do not account for these factors. A Category IV designation would acknowledge the severity and the increased risk of progression. Subsequently, patient management would be optimized with wound care and the appropriate administration of rabies-immune globulin/monoclonal antibodies (RIG/MAbs). All Category IV exposures would be infiltrated with the full dose of intact RIG (i.e., human RIG or MAbs) if the patient was previously unvaccinated. More concentrated RIG/MAb formulations would be preferred. As a world rabies community, we cannot tolerate PEP failures. A fourth WHO categorization will improve the care of these high-risk patients and highlight the global health urgency of this neglected disease.

In vitro and in vivo evaluation of a single chain antibody fragment generated in planta with potent rabies neutralisation activity

Rabies causes more than 60,000 human deaths annually in areas where the virus is endemic. Importantly, rabies is one of the few pathogens for which there is no treatment following the onset of clinical disease with the outcome of infection being death in almost 100% of cases. Whilst vaccination, and the combination of vaccine and rabies immunoglobulin treatment for post-exposure administration are available, no tools have been identified that can reduce or prevent rabies virus replication once clinical disease has initiated. The search for effective antiviral molecules to treat those that have already developed clinical disease associated with rabies virus infection is considered one of the most important goals in rabies research. The current study assesses a single chain antibody molecule (ScFv) based on a monoclonal antibody that potently neutralises rabies in vitro as a potential therapeutic candidate. The recombinant ScFv was generated in Nicotiana benthamiana by transient expression, and was chemically conjugated (ScFv/RVG) to a 29 amino acid peptide, specific for nicotinic acetylcholine receptor (nAchR) binding in the CNS. This conjugated molecule was able to bind nAchR in vitro and enter neuronal cells more efficiently than ScFv. The ability of the ScFv/RVG to neutralise virus in vivo was assessed using a staggered administration where the molecule was inoculated either four hours before, two days after or four days after infection. The ScFv/RVG conjugate was evaluated in direct comparison with HRIG and a potential antiviral molecule, Favipiravir (also known as T-705) to indicate whether there was greater bioavailability of the ScFv in the brains of treated mice. The study indicated that the approach taken with the ScFv/RVG conjugate may have utility in the design and implementation of novel tools targetting rabies virus infection in the brain.

Rabies

Rabies is a life-threatening neglected tropical disease: tens of thousands of cases are reported annually in endemic countries (mainly in Africa and Asia), although the actual numbers are most likely underestimated. Rabies is a zoonotic disease that is caused by infection with viruses of the Lyssavirus genus, which are transmitted via the saliva of an infected animal. Dogs are the most important reservoir for rabies viruses, and dog bites account for >99% of human cases. The virus first infects peripheral motor neurons, and symptoms occur after the virus reaches the central nervous system. Once clinical disease develops, it is almost certainly fatal. Primary prevention involves dog vaccination campaigns to reduce the virus reservoir. If exposure occurs, timely post-exposure prophylaxis can prevent the progression to clinical disease and involves appropriate wound care, the administration of rabies immunoglobulin and vaccination. A multifaceted approach for human rabies eradication that involves government support, disease awareness, vaccination of at-risk human populations and, most importantly, dog rabies control is necessary to achieve the WHO goal of reducing the number of cases of dog-mediated human rabies to zero by 2030.

Injecting rabies immunoglobulin (RIG) into wounds only: A significant saving of lives and costly RIG

An increasing number of dog bite victims were being presented to public hospitals in Himachal Pradesh in 2014 amidst virtual non availability of any rabies immunoglobulin (RIG). Only a small quantity of equine rabies immunoglobulin (eRIG) was available from the government owned Central Research Institute (CRI) Kasauli. This available eRIG was used in 269 patients as an emergency response and only for local infiltration of severe bite wounds by suspected rabid dogs. This was followed by rabies vaccination, using the WHO approved intra-dermal Thai Red Cross Society vaccination schedule. A subgroup of 26 patients were later identified who had been severely bitten by laboratory confirmed rabid dogs. They were followed for more than one year and all were found to be alive.

Four Thousand Years of Concepts Relating to Rabies in Animals and Humans, Its Prevention and Its Cure

The epitome of the One Health paradigm-and of its shortcomings-rabies has been known to humankind for at least 4000 years. We review the evolution through history of concepts leading to our current understanding of rabies in dogs and humans and its prevention, as transmitted by accessible and surviving written texts. The tools and concepts currently available to control rabies were developed at the end of the 19th Century, including the first live, attenuated vaccine ever developed for humans and the first post-exposure prophylaxis (PEP) regimen. No progress, however, has been made in etiological treatment, leaving clinicians who provide care to animals or patients with symptomatic rabies as powerless today as their colleagues in Mesopotamia, 40 centuries ago. Rabies remains to date the most lethal infectious disease known to humans. Widespread access to timely, effective, and affordable PEP in rural areas of developing countries is urgently needed.

Development of broad-spectrum human monoclonal antibodies for rabies post-exposure prophylaxis

Currently available rabies post-exposure prophylaxis (PEP) for use in humans includes equine or human rabies immunoglobulins (RIG). The replacement of RIG with an equally or more potent and safer product is strongly encouraged due to the high costs and limited availability of existing RIG. In this study, we identified two broadly neutralizing human monoclonal antibodies that represent a valid and affordable alternative to RIG in rabies PEP. Memory B cells from four selected vaccinated donors were immortalized and monoclonal antibodies were tested for neutralizing activity and epitope specificity. Two antibodies, identified as RVC20 and RVC58 (binding to antigenic site I and III, respectively), were selected for their potency and broad-spectrum reactivity. In vitro, RVC20 and RVC58 were able to neutralize all 35 rabies virus (RABV) and 25 non-RABV lyssaviruses. They showed higher potency and breath compared to antibodies under clinical development (namely CR57, CR4098, and RAB1) and commercially available human RIG. In vivo, the RVC20-RVC58 cocktail protected Syrian hamsters from a lethal RABV challenge and did not affect the endogenous hamster post-vaccination antibody response.

Protective effect of different anti-rabies virus VHH constructs against rabies disease in mice

Rabies virus causes lethal brain infection in about 61000 people per year. Each year, tens of thousands of people receive anti-rabies prophylaxis with plasma-derived immunoglobulins and vaccine soon after exposure. Anti-rabies immunoglobulins are however expensive and have limited availability. VHH are the smallest antigen-binding functional fragments of camelid heavy chain antibodies, also called Nanobodies. The therapeutic potential of anti-rabies VHH was examined in a mouse model using intranasal challenge with a lethal dose of rabies virus. Anti-rabies VHH were administered directly into the brain or systemically, by intraperitoneal injection, 24 hours after virus challenge. Anti-rabies VHH were able to significantly prolong survival or even completely rescue mice from disease. The therapeutic effect depended on the dose, affinity and brain and plasma half-life of the VHH construct. Increasing the affinity by combining two VHH with a glycine-serine linker into bivalent or biparatopic constructs, increased the neutralizing potency to the picomolar range. Upon direct intracerebral administration, a dose as low as 33 µg of the biparatopic Rab-E8/H7 was still able to establish an anti-rabies effect. The effect of systemic treatment was significantly improved by increasing the half-life of Rab-E8/H7 through linkage with a third VHH targeted against albumin. Intraperitoneal treatment with 1.5 mg (2505 IU, 1 ml) of anti-albumin Rab-E8/H7 prolonged the median survival time from 9 to 15 days and completely rescued 43% of mice. For comparison, intraperitoneal treatment with the highest available dose of human anti-rabies immunoglobulins (65 mg, 111 IU, 1 ml) only prolonged survival by 2 days, without rescue. Overall, the therapeutic benefit seemed well correlated with the time of brain exposure and the plasma half-life of the used VHH construct. These results, together with the ease-of-production and superior thermal stability, render anti-rabies VHH into valuable candidates for development of alternative post exposure treatment drugs against rabies.

Passive immunity in the prevention of rabies

Prevention of clinical disease in those exposed to viral infection is an important goal of human medicine. Using rabies virus infection as an example, we discuss the advances in passive immunoprophylaxis, most notably the shift from the recommended polyclonal human or equine immunoglobulins to monoclonal antibody therapies. The first rabies-specific monoclonal antibodies are undergoing clinical trials, so passive immunisation might finally become an accessible, affordable, and routinely used part of global health practices for rabies. Coupled with an adequate supply of modern tissue-culture vaccines, replacing the less efficient and unsafe nerve-tissue-derived rabies vaccines, the burden of this disease could be substantially reduced.

Rabies post-exposure prophylaxis in the Philippines: health status of patients having received purified equine F(ab')(2) fragment rabies immunoglobulin (Favirab)

BACKGROUND

Recommended treatment for severe rabies exposure in unvaccinated individuals includes wound cleaning, administration of rabies immunoglobulins (RIG), and rabies vaccination. We conducted a survey of rabies treatment outcomes in the Philippines.

METHODS

This was a case series involving 7,660 patients (4 months to 98 years of age) given purified equine RIG (pERIG) at the Research Institute for Tropical Medicine (Muntinlupa, Philippines) from July 2003 to August 2004 following Category II or III exposures. Data on local and systemic adverse reactions (AR) within 28 days and biting animal status were recorded; outcome data were obtained by telephone or home visit 6-29 months post-exposure.

RESULTS

Follow-up data were collected for 6,464 patients. Of 151 patients with laboratory-confirmed rabies exposure, 143 were in good health 6-48 months later, seven could not be contacted, and one 4-year-old girl died. Of 16 deaths in total, 14 were unrelated to rabies exposure or treatment. Two deaths were considered PEP failures: the 4-year old girl, who had multiple deep lacerated wounds from a rabid dog of the nape, neck, and shoulders requiring suturing on the day of exposure, and an 8-year-old boy who only received rabies PEP on the day of exposure.

CONCLUSIONS

This extensive review of outcomes in persons with Category III exposure shows the recommended treatment schedule at RITM using pERIG is well tolerated, while survival of 143 laboratory-confirmed rabies exposures confirms the intervention efficacy. Two PEP intervention failures demonstrate that sustained education and training is essential in rabies management.

Human monoclonal antibody and vaccine approaches to prevent human rabies

Rabies, being a major zoonotic disease, significantly impacts global public health. It is invariably fatal once clinical signs are apparent. The majority of human rabies deaths occur in developing countries. India alone reports more than 50% of the global rabies deaths. Although it is a vaccine-preventable disease, effective rabies prevention in humans with category III bites requires the combined administration of rabies immunoglobulin (RIG) and vaccine. Cell culture rabies vaccines have become widely available in developing countries, virtually replacing the inferior and unsafe nerve tissue vaccines. Limitations inherent to the conventional RIG of either equine or human origin have prompted scientists to look for monoclonal antibody-based human RIG as an alternative. Fully human monoclonal antibodies have been found to be safer and equally efficacious than conventional RIG when tested in mice and hamsters. In this chapter, rabies epidemiology, reservoir control measures, post-exposure prophylaxis of human rabies, and combination therapy for rabies are discussed. Novel human monoclonal antibodies, their production, and the significance of plants as expression platforms are emphasized.

Failures of post-exposure rabies prophylaxis

Rabies remains a public health problem in many emerging countries. Virtually all is known that should enable us to eliminate this scourge by controlling the disease in canine populations and by diligent provision of WHO recommended post-exposure prophylaxis (PEP). Nevertheless, post-exposure prophylaxis failures do occur. Most common failures are due to deviations from WHO management recommendations and lack of essential biologicals. True failures, where all was done according to WHO recommendations, are fortunately extremely rare. Presented are seven such deaths. Other examples of common management deviations that resulted in deaths are also shown.

Identification and characterization of a human monoclonal antibody that potently neutralizes a broad panel of rabies virus isolates

Rabies is a zoonosis that results in millions of human exposures worldwide each year. Human monoclonal antibodies (HuMAbs) that neutralize rabies virus may represent one viable strategy for post-exposure prophylaxis in humans, and have many advantages over current human or equine rabies immune globulin. Transgenic mice carrying human immunoglobulin genes were used to isolate human monoclonal antibodies that neutralized rabies virus. Several HuMAbs were identified that neutralized rabies virus variants from a broad panel of isolates of public health significance. HuMAb 17C7 was the most promising antibody identified because it neutralized all rabies virus isolates tested. HuMAb 17C7 recognizes a conformational epitope on the rabies virus glycoprotein which includes antigenic site III. HuMAb 17C7 protected hamsters from a lethal dose of rabies virus in a well-established in vivo model of post-exposure prophylaxis.

Renal involvement in human rabies: clinical manifestations and autopsy findings of nine cases from northeast of Brazil

A retrospective study was conducted in nine patients with rabies admitted to a hospital of Fortaleza, Brazil. Autopsy was performed in all cases. The ages ranged from three to 81 years and six were males. They all were bitten by dogs. The time between the accident and the hospital admission ranged from 20 to 120 days (mean 45 +/- 34 days). The time until death ranged from one to nine days (mean 3.3 +/- 5.5 days). The signs and symptoms presented were fever, hydrophobia, aerophobia, agitation, disorientation, dyspnea, sialorrhea, vomiting, oliguria, sore throat, pain and hypoesthesia in the site of the bite, headache, syncope, cough, hematemesis, mydriasis, hematuria, constipation, cervical pain and priapism. In three out of six patients, there was evidence of acute renal failure, defined as serum creatinine > or = 1.4 mg/dL. The post-mortem findings in the kidneys were mild to moderate glomerular congestion and mild to intense peritubular capillary congestion. Acute tubular necrosis was seen in only two cases. This study shows some evidence of renal involvement in rabies. Histopathologic findings are nonspecific, so hemodynamic instability, caused by autonomic dysfunction, hydrophobia and dehydration must be responsible for acute renal failure in rabies.

Novel human monoclonal antibody combination effectively neutralizing natural rabies virus variants and individual in vitro escape mutants

The need to replace rabies immune globulin (RIG) as an essential component of rabies postexposure prophylaxis is widely acknowledged. We set out to discover a unique combination of human monoclonal antibodies (MAbs) able to replace RIG. Stringent criteria concerning neutralizing potency, affinity, breadth of neutralization, and coverage of natural rabies virus (RV) isolates and in vitro escape mutants were set for each individual antibody, and the complementarities of the two MAbs were defined at the onset. First, we identified and characterized one human MAb (CR57) with high in vitro and in vivo neutralizing potency and a broad neutralization spectrum. The linear antibody binding site was mapped on the RV glycoprotein as antigenic site I by characterizing CR57 escape mutants. Secondly, we selected using phage display a complementing antibody (CR4098) that recognized a distinct, nonoverlapping epitope (antigenic site III), showed similar neutralizing potency and breadth as CR57, and neutralized CR57 escape mutants. Reciprocally, CR57 neutralized RV variants escaping CR4098. Analysis of glycoprotein sequences of natural RV isolates revealed that the majority of strains contain both intact epitopes, and the few remaining strains contain at least one of the two. In vitro exposure of RV to the combination of CR57 and CR4098 yielded no escape mutants. In conclusion, a novel combination of human MAbs was discovered suitable to replace RIG.

Emergency vaccination of rabies under limited resources -- combating or containing?

Background

Rabies is the most important viral zoonosis from a global perspective. Worldwide efforts to combat the disease by oral vaccination of reservoirs have managed to eradicate wildlife rabies in large areas of central Europe and North-America. Thus, repeated vaccination has been discontinued recently on a geographical scale. However, as rabies has not yet been eradicated globally, a serious risk of re-introduction remains. What is the best spatial design for an emergency vaccination program – particularly if resources are limited? Either, we treat a circular area around the detected case and run the risk of infected hosts leaving the limited control area, because a sufficient immunisation level has not yet been built up. Or, initially concentrate the SAME resources in order to establish a protective ring which is more distant from the infected local area, and which then holds out against the challenge of the approaching epidemic.

Methods

We developed a simulation model to contrast the two strategies for emergency vaccination. The spatial-explicit model is based on fox group home-ranges, which facilitates the simulation of rabies spread to larger areas relevant to management. We used individual-based fox groups to follow up the effects of vaccination in a detailed manner. Thus, regionally – bait distribution orientates itself to standard schemes of oral immunisation programs and locally – baits are assigned to individual foxes.

Results

Surprisingly, putting the controlled area ring-like around the outbreak does not outperform the circular area of the same size centred on the outbreak. Only during the very first baitings, does the ring area result in fewer breakouts. But then as rabies is eliminated within the circle area, the respective ring area fails, due to the non-controlled inner part.

We attempt to take advantage of the initially fewer breakouts beyond the ring when applying a mixed strategy. Therefore, after a certain number of baitings, the area under control was increased for both strategies towards the same larger circular area. The circle-circle strategy still outperforms the ring-circle strategy and analysis of the spatial-temporal disease spread reveals why: improving control efficacy by means of a mixed strategy is impossible in the field, due to the build-up time of population immunity.

Conclusion

For practical emergency management of a new outbreak of rabies, the ring-like application of oral vaccination is not a favourable strategy at all. Even if initial resources are substantially low and there is a serious risk of rabies cases outside the limited control area, our results suggest circular application instead of ring vaccination.

Efficacy of rabies immunoglobulins in an experimental post-exposure prophylaxis rodent model

In a recently published Syrian hamster animal challenge study [Vaccine 19 (2001) 2273], a highly purified, heat-treated equine rabies immunoglobulin (pERIG HT, Favirab) did not elicit satisfactory protection. The efficacies of this batch, a second stage pERIG HT batch and reference RIG preparations (Imorab, Imogam Rage pasteurised, Berna antiserum) were compared in mice challenged with either Ariana canine field strain or CVS strain. Survival rates against Ariana challenge with the second pERIG HT batch were indistinguishable from those of other licensed preparations (83-90% survival), but the deficient batch did not provide satisfactory protection (53%). These data confirm the inadequate response to a first stage pERIG HT batch, but a current batch provides equivalent protection to that afforded by licensed HRIG and ERIG preparations.

Rabies update for travel medicine advisors

Rabies is a neglected disease in many developing countries. It is preventable, and the tools to prevent it are known. There is urgent need for more funding, for study of innovative dog population-control measures, and for sustainable canine immunization. Safe and effective tissue-culture rabies vaccines and human and equine rabies immunoglobulins (HRIG and ERIG) are not readily available in many regions where rabies is endemic. This and the continuing presence and spread of rabies have increased the risk for travelers, who cannot rely on being able to receive optimal postexposure treatment in many parts of the world. Alternatives to HRIG or ERIG are not available. Travelers who leave the safe environments of tourist hotels and buses in regions of Asia, Russia, Africa, and Latin America where canine rabies is endemic may be at risk of life-threatening exposure to rabies.

Public health surveillance for Australian bat lyssavirus in Queensland, Australia, 2000-2001

From February 1, 2000, to December 4, 2001, a total of 119 bats (85 Megachiroptera and 34 Microchiroptera) were tested for Australian bat lyssavirus (ABLV) infection. Eight Megachiroptera were positive by immunofluorescence assay that used cross-reactive ntibodies to rabies nucleocapsid protein. A case study of cross-species transmission of ABLV supports the conclusion that a bat reservoir exists for ABLV in which the virus circulates across Megachiroptera species within mixed communities.

Postexposure prophylaxis for prevention of rabies in dogs

OBJECTIVE

To evaluate postexposure prophylaxis (PEP) in dogs experimentally infected with rabies.

ANIMALS

29 Beagles.

PROCEDURE

Dogs were sedated and inoculated in the right masseter muscle with a salivary gland homogenate from a naturally infected rabid dog (day 0). Six hours later, 5 dogs were treated by administration of 2 murine anti-rabies glycoprotein monoclonal antibodies (mAb) and commercial vaccine; 5 received mAb alone; 5 received purified, heat-treated, equine rabies immune globulin (PHT-ERIG) and vaccine; 5 received PHT-ERIG alone; 4 received vaccine alone; and 5 control dogs were not treated. The mAb or PHT-ERIG was administered at the site of rabies virus inoculation. Additional vaccine doses for groups mAb plus vaccine, PHT-ERIG plus vaccine, and vaccine alone were administered IM in the right hind limb on days 3, 7, 14, and 35.

RESULTS

All control dogs and dogs that received only vaccine developed rabies. In the PHT-ERIG and vaccine group, 2 of 5 dogs were protected, whereas none were protected with PHT-ERIG alone. Use of mAb alone resulted in protection in 4 of 5 dogs. Administration of mAb in combination with vaccine provided protection in all 5 dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Current national guidelines recommend euthanasia or a 6-month quarantine for unvaccinated animals exposed to rabies. Findings from this study document that vaccine alone following severe exposure was unable to provide protection from rabies. However, vaccine combined with mAb resulted in protection in all treated dogs, revealing the potential use of mAb in PEP against rabies in naive dogs.

Update on rabies

Rabies remains an important public health problem worldwide due to endemic dog rabies in developing countries. Rabies was a re-emerging disease in the United States during the 1990s due to bat rabies virus variants. Australian bat lyssavirus also emerged in Australian bat populations and caused two human deaths. There have been important recent advances in our knowledge of the pathogenesis of rabies and in our ability to diagnose and prevent it.

Rabies re-examined

Rabies is an acute, progressive, incurable viral encephalitis. The causative agents are neurotropic RNA viruses in the family Rhabdoviridae, genus Lyssavirus. Mammalian reservoirs include the Carnivora and Chiroptera, but rabid dogs still pose the greatest hazard worldwide. Viral transmission occurs mainly via animal bite, and once the virus is deposited in peripheral wounds, centripetal passage occurs towards the central nervous system. After viral replication, there is centrifugal spread to major exit portals, the salivary glands. The epidemiological significance of any host "carrier" state remains highly speculative. Although incubation periods average 1-3 months, disease occurrence days or years after exposure has been documented. Rabies should be suspected in patients with a concomitant history of animal bite and traditional clinical presentation, but a lack of such clues makes antemortem diagnosis a challenge. Pathogenetic mechanisms remain poorly understood, and current care entails palliative measures only. Current medical emphasis relies heavily on prevention of exposure and intervention before clinical onset. Prophylaxis encompasses thorough wound treatment, vaccine administration, and inoculation of rabies immunoglobulin. Although it is a major zoonosis, canine rabies can be eliminated, and application of new vaccine technologies permits significant disease control among wildlife species. Nevertheless, despite much technical progress in the past century, rabies is a disease of neglect and presents a modern public-health conundrum.

Rabies DNA vaccination of non-human primates: post-exposure studies using gene gun methodology that accelerates induction of neutralizing antibody and enhances neutralizing antibody titers

Pre-exposure DNA vaccination protects non-human primates against rabies virus. Post-exposure protection of monkeys against rabies virus by DNA vaccination has not been attempted. Presumably, post-exposure experiments have not been undertaken because neutralizing antibody is usually slow to be induced after DNA vaccination. In this study, we initially attempted to accelerate the induction of neutralizing antibody by varying the route and site of DNA vaccination and booster frequency. Gene gun (GG) vaccinations above axillary and inguinal lymph nodes or in ear pinnae generated higher levels of neutralizing antibody than intradermal (ID) needle vaccinations in the pinnae. Concurrent GG booster vaccinations above axillary and inguinal lymph nodes and in ear pinnae, 3 days after primary vaccination, accelerated detectable neutralizing antibody. GG booster vaccinations also resulted in higher neutralizing antibody levels and increased the durability of this response. Post-exposure vaccination with DNA or the human diploid cell vaccine (HDCV), in combination with an one-time treatment with human rabies immune globulin (HRIG), protected 50 and 75% of the monkeys, respectively, as compared to 75% mortality of the controls. These data will be useful for the refinement, development, and implementation of future pre- and post-exposure rabies DNA vaccination studies.

Postexposure treatment of rabies infection: can it be done without immunoglobulin?

The last remaining international manufacturer of equine rabies immunoglobulin (ERIG) discontinued production in 2001. However, ERIG remains an essential biological that has no substitute other than human rabies immunoglobulin (HRIG), which is in short supply and virtually unaffordable in developing countries. Physicians in regions where canine rabies is endemic and neither ERIG nor HRIG is available are providing less-than-optimal treatment to patients exposed to rabies. If no immunoglobulin is available, they have only 1 therapy option: use of a vaccine schedule that produces the highest and, hopefully, earliest neutralizing antibody response. However, treatment failures must still be expected. Early, aggressive wound cleansing and more intensive efforts at canine control and are ever more important. Countries that have the resources to manufacture their own rabies immunoglobulins must be encouraged to do so.