G M Baer

Centers for Disease Control and Prevention, Atlanta, Michigan, United States

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Publications (64)513.09 Total impact

  • Jean S. Smith, Pamela A. Yager, George M. Baer
    Annals of the New York Academy of Sciences 12/2006; 350(1):568 - 569. DOI:10.1111/j.1749-6632.1980.tb20659.x · 4.31 Impact Factor
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    ABSTRACT: The National Institutes of Health (NIH) rabies vaccine potency test is used internationally for evaluating the efficacy of inactivated rabies vaccines, despite concerns about its methods. An alternative test has been developed, using a simplified in vivo method for rabies vaccine testing which has several advantages over the currently recommended method of efficacy testing. The rabies peripheral challenge test more closely models practical vaccine application in target species; decreases the observed effect of vaccine virus strain in testing results and allows sensitive analysis of vaccine and production lot testing.
    Vaccine 12/2006; 24(49-50):7115-23. DOI:10.1016/j.vaccine.2006.06.078 · 3.49 Impact Factor
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    ABSTRACT: To evaluate the effect of various routes of administration and number of doses of 3 commercially produced rabies vaccines on serum antibody responses and protection in mice challenged by intracerebral injection with fixed-strain rabies virus. 2,213 mice. Inactivated, adjuvanted rabies vaccines were administered to mice in either 2, 1, or 0 (control) doses via IP, IM, and SC routes, and mice were challenged intracerebrally with fixed-strain rabies virus. Vaccination route and dose number significantly influenced serum antibody responses and protection from rabies virus challenge, independent of vaccine strain origin and mouse strain, although mouse age significantly affected results. Extended challenge studies revealed that IM vaccination of mice resulted in the highest serum neutralizing antibody responses and protection levels equivalent to IP vaccination. Even multiple doses administered SC (a vaccination route used in dogs) resulted in poor serum anti-rabies neutralizing antibody responses in mice and were far less protective than other routes. Findings suggest possible improvements for the current rabies vaccine potency test in mice by using 1 dose, the IM route, and a delayed time of challenge. These modifications would more closely model vaccination practices in target species and yield more accurate information regarding primary immunogenicity of a vaccine.
    American Journal of Veterinary Research 05/2003; 64(4):491-8. DOI:10.2460/ajvr.2003.64.491 · 1.21 Impact Factor
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    ABSTRACT: To determine effect of route of challenge and strain of rabies virus on efficacy of inactivated rabies vaccines in mice. 3,056 mice. Challenge was performed with fixed and street rabies virus strains by use of footpad and intracerebral routes as well as IM injection into the hip, shoulder, neck, and masseter muscles. Intraperitoneal and IM vaccination was performed with 1 or 2 doses of 1 of 3 vaccine-strain inactivated rabies vaccines. For 2 of the vaccine strains, the vaccines were adjuvanted and nonadjuvanted. Incubation periods were dependent on route, dose, and virus strain used for challenge. Use of an intramasseter challenge route with challenge virus-strain rabies virus, which more accurately models natural exposure to rabies virus, resulted in reproducible mortality rates in mice. Use of this route revealed that differences among vaccines and challenge virus strains affected mortality rate less than that observed in the National Institutes of Health potency test, even when street isolates of widely variant origin were used for challenge. These results, combined with earlier data, support a proposal for a new rabies potency test that more closely models current vaccine administration practices and natural infection routes.
    American Journal of Veterinary Research 05/2003; 64(4):499-505. DOI:10.2460/ajvr.2003.64.499 · 1.21 Impact Factor
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    ABSTRACT: The safety of two attenuated oral rabies vaccines was evaluated in mink and in five species of rodents which occur in the Arctic. A 0.03 ml sample of liquid vaccine was installed directly into the mouth of voles and lemmings and 0.1 ml into the mouth of Arctic ground squirrels and mink. Animals were euthanized at 36 and 46 days postexposure; brain tissue was analyzed by FAT and serum by RFFIT. No rabies deaths occurred in 47 animals tested. Four animals representing three rodent species seroconverted, the highest titer being 0.5 IU ml-1. The absence of rabies virus in brain tissue indicates the safety of these vaccines in these species. The replacement of arginine with glutamic acid at position 333 reduces the pathogenicity of these vaccines, thereby presumably preventing the deleterious effect of viral entry into CNS neurons.
    Vaccine 04/1996; 14(4):270-3. DOI:10.1016/0264-410X(95)00208-I · 3.49 Impact Factor
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    ABSTRACT: From 1 July 1987 to 31 December 1988, 30% of 247 rabid dogs in Hermosillo, Mexico had a positive history of rabies vaccination. Serosurveys suggested that inactivated suckling mouse brain vaccine (INACT-SMBV) and inactivated tissue culture vaccine (INACT-TC) used before and during the epizootic were poor immunogens. Prospective studies showed that only about one-third of dogs vaccinated with INACT-SMBV were seropositive 5 weeks after vaccination. Lack of vaccine potency was the most likely cause of poor immunogenicity. Rabies vaccines should be evaluated periodically by measuring antibody responses in animals. In some circumstances, minimum seroconversion rates and antibody titres in vaccinated animals may be better measures of immunogenicity than relative potency.
    Vaccine 12/1994; 12(14):1259-64. DOI:10.1016/S0264-410X(94)80049-6 · 3.49 Impact Factor
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    ABSTRACT: Dogs were vaccinated intradermally with vaccinia virus recombinants expressing the rabies virus glycoprotein (G protein) or nucleoprotein (N protein) or a combination of both proteins. The dogs vaccinated with either the G or G plus N proteins developed virus-neutralizing antibody titers, whereas those vaccinated with only the N protein did not. All dogs were then challenged with a lethal dose of a street rabies virus, which killed all control dogs. Dogs vaccinated with the G or G plus N proteins were protected. Five (71%) of seven dogs vaccinated with the N protein sickened, with incubation periods 3 to 7 days shorter than that of the control dogs; however, three (60%) of the five rabid dogs recovered without supportive treatment. Thus, five (71%) of seven vaccinated with the rabies N protein were protected against a street rabies challenge. Our data indicate that rabies virus N protein may be involved in reducing the incubation period in dogs primed with rabies virus N protein and then challenged with a street rabies virus and, of more importance, in subsequent sickness and recovery.
    Journal of Virology 06/1992; 66(5):2601-4. · 4.65 Impact Factor
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    ABSTRACT: Arctic foxes were immunized with the SAG1 oral rabies vaccine. The effectiveness was determined by the serological response and by the survival to a challenge dose of rabies virus from an Alaskan fox. Vaccine virus was isolated from saliva 1 h after the liquid vaccine was placed directly into the mouth but not subsequently (tested up to 1 week postvaccination). Two weeks after vaccination, protective antibody levels were present in all foxes and all vaccinated foxes survived challenge at 9 weeks postvaccination. At 26 weeks postvaccination (17 weeks postchallenge) all but one fox had detectable antibody levels. Neural tissue harvested from surviving foxes was negative for rabies virus by direct immunofluorescent testing. One of the foxes vaccinated with SAG1 seroconverted and survived challenge even though the titre of the vaccine used was almost 4 logs less than that used to vaccinate the other foxes. These results suggest that the avirulent SAG1 oral rabies vaccine is very effective in protecting arctic foxes.
    Vaccine 02/1992; 10(5):305-8. DOI:10.1016/0264-410X(92)90368-T · 3.49 Impact Factor
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    ABSTRACT: Twenty nine skunks (Mephitis mephitis) were vaccinated orally with raccoon poxvirus (RCN) recombinants: 10 with a recombinant expressing the rabies virus glycoprotein (RCNRG), 10 with RCNRG mixed with a recombinant expressing the rabies virus nucleoprotein (RCNRN) and nine with RCN alone. Rabies virus neutralizing antibodies were detected in six of the 20 skunks; five skunks (three given RCNRG, two given a mixture of recombinants) survived a rabies challenge that was lethal for nine skunks vaccinated with RCN alone.
    Journal of wildlife diseases 11/1991; 27(4):681-4. DOI:10.7589/0090-3558-27.4.681 · 1.31 Impact Factor
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    ABSTRACT: Intraperitoneal vaccination of mice with rabies vaccine results in both dosage-dependent rabies virus neutralizing antibody titres and protection from lethal intracerebral (i.c.) challenge with fixed strain CVS rabies virus. Pre-exposure adoptive intravenous transfer of naive or immune cells did not significantly protect naive Balb/c mice from lethal i.c. CVS challenge, but immune serum and anti-rabies glycoprotein monoclonal antibodies (individually and in combination) did confer significant protection when administered before or up to 24 h after lethal i.c. rabies virus challenge.
    Vaccine 10/1991; 9(9):638-42. DOI:10.1016/0264-410X(91)90188-C · 3.49 Impact Factor
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    ABSTRACT: The 2-1-1 rabies postexposure treatment schedule is an abbreviated regimen in which a tissue culture rabies vaccine is administered intramuscularly at two sites on day 0, and at one site on days 7 and 21. Compared to the standard five-dose intramuscular regimen, the 2-1-1 schedule reduces the number of clinic visits from five to three and the amount of vaccine used by 20%. One hundred Thai patients, who were severely exposed to rabies, were treated with rabies immune globulin and the 2-1-1 regimen using purified Vero cell rabies vaccine. They were followed for 1 year. Rabies antibody titres were measured in 10% of this group. All patients survived and adverse reactions were mild. A satisfactory antibody response (a titre > 0.5 IU ml−1) occurred in all ten patients studied at day 14, but persisted for 90 days in 80% and for 360 days in only 50%. The authors therefore do not recommend use of the 2-1-1 schedule in severely exposed patients who also need to receive rabies immune globulin.
    Vaccine 09/1991; 9(8-9):573-576. DOI:10.1016/0264-410X(91)90244-Z · 3.49 Impact Factor
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    ABSTRACT: Captive raccoons were offered a variety of vaccine containers and bait components in a series of three-choice tests. Paraffin wax ampules were the most readily accepted vaccine container. Preferred bait components included corn and shellfish oils, deep fried corn meal batter, and egg, apple and buttermilk flavorings. These results, together with factors including ease of bait formulation, cost, and suitability for field use, were used to develop an experimental delivery system for an oral rabies vaccine. The developed system was composed of a polyurethane sleeve (1.5 x 5.5 cm) dipped in a commercial food batter mix together with corn meal, milk and egg. The sleeve was deep fried in corn oil and a 2.0 ml ampule containing a recombinant rabies vaccine was then inserted into the sleeve bait. These baits were presented to 10 captive raccoons. Nine of the 10 animals developed high levels of rabies virus neutralizing antibodies. Field tests are needed to determine if the delivery system developed also is effective for wild raccoons.
    Journal of wildlife diseases 02/1991; 27(1):21-33. DOI:10.7589/0090-3558-27.1.21 · 1.31 Impact Factor
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    ABSTRACT: The Thai Red Cross intradermal postexposure rabies treatment schedule was prospectively assessed in 100 Thai patients severely bitten by proven rabid animals. It consists of 0.1 ml of purified Vero cell rabies vaccine containing more than 2.5 IU of rabies antigen per 0.5 ml of reconstituted vaccine given intradermally at two sites on days 0, 3, and 7, followed by one 0.1 ml injection on days 30 and 90. The commercial vaccine used had an antigen content of 3.17 IU per 0.5 ml ampoule. Purified equine or human rabies immuno-globulin was also given on day 0 to patients with severe exposures. As much of the immunoglobulin as possible was infiltrated around the wounds. All patients were followed for 1 year post exposure. There were no deaths; the efficacy of the regimen was 100%. Antibody titre determination in a randomly selected subgroup showed seroconversion in all 10 patients.
    The Lancet 05/1990; 335(8694):896-8. DOI:10.1016/0140-6736(90)90488-Q · 39.21 Impact Factor
  • The Lancet 04/1990; 335(8690):664-5. DOI:10.1016/0140-6736(90)90454-D · 39.21 Impact Factor
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    ABSTRACT: In summer 1986, a study was conducted to evaluate raccoon (Procyon lotor) acceptance of oral baits that could be used for rabies vaccination. One thousand wax-coated sponge bait cubes were filled with 5 mg of a seromarker (iophenoxic acid), placed in polyethylene bags, and hand-distributed in an 80 ha area within an urban National Park in Washington, D. C. (USA). After 3 wk, target and nontarget animals were trapped and blood samples collected to evaluate bait uptake. Thirty-three of 52 (63%) raccoons had elevated blood iodine levels indicating they had eaten at least one bait, 13 (25%) were negative, and six (12%) had marginal values. These results indicate that sponge baits hand-placed at a density of 12.4/ha can reach a significant proportion of an urban raccoon population. Implications for oral rabies vaccination of raccoons are discussed.
    Journal of wildlife diseases 02/1989; 25(1):1-9. DOI:10.7589/0090-3558-25.1.1 · 1.31 Impact Factor
  • D B Fishbein, G M Baer
    Annals of internal medicine 01/1989; 109(12):935-7. · 16.10 Impact Factor
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    ABSTRACT: Two infectious raccoon poxvirus (RCN) recombinants for expressing rabies virus surface spike glycoprotein (G) were produced by homologous recombination between raccoon poxvirus DNA and chimeric plasmids previously used for production of vaccinia virus recombinants. Expression of G protein was controlled by vaccinia virus promoter P7.5 (early/late class) or by P11 (late class). Immunoprecipitation of infected cell extracts indicated that both of the RCN recombinants directed faithful expression of G protein. Raccoons that were fed polyurethane baits loaded with either recombinant quickly developed high levels of rabies virus neutralizing antibodies and were protected when challenged with lethal raccoon rabies street virus.
    Virology 08/1988; 165(1):313-6. DOI:10.1016/0042-6822(88)90692-7 · 3.28 Impact Factor
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    ABSTRACT: Arctic foxes (Alopex lagopus) were successfully immunized against rabies using an orally-administered, liquid SAD-BHK21 live virus vaccine in a sausage bait. Immunization was determined by serologic response and by resistance to challenge with an arctic rabies virus strain. Virus was not shed in saliva following oral vaccination, indicating that arctic foxes would not infect other foxes after ingesting this vaccine. High antibody levels were present in all experimental foxes 2 wk following initial vaccination. A booster vaccination at 56 wk induced a significant serologic response within 1 wk, suggesting an anamnestic response but titers began to decline within 8 wk in most foxes. Foxes were observed for 16 mo following the challenge and exhibited no symptoms of rabies. The SAD-BHK21 rabies vaccine in a sausage bait system has a strong potential for vaccinating wild populations of arctic fox.
    Journal of wildlife diseases 08/1988; 24(3):477-83. DOI:10.7589/0090-3558-24.3.477 · 1.31 Impact Factor
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    ABSTRACT: An attenuated strain of canine adenovirus type-2 (CAV-2) was administered orally to 2 foxes (Vulpes fulva), 6 raccoons (Procyon lotor), a skunk (Mephitis mephitis), and a mongoose (Herpestus auropunctatus). Blood was collected weekly from the animals to monitor CAV-2 virus-neutralizing antibody titers. All animals had increases in titers. Sera from 8 foxes, 30 mongooses, 52 raccoons, and 22 skunks trapped in the field had naturally occurring antibody to CAV-2.
    American Journal of Veterinary Research 03/1988; 49(2):169-71. · 1.21 Impact Factor
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    ABSTRACT: We have developed an enzyme immunoassay for rabies virus by using acetone-fixed infected cell cultures as the antigen. This test was used to demonstrate virus-neutralizing antibodies in human and animal sera and was as sensitive as and easier to perform than the rapid fluorescent-focus inhibition technique.
    Journal of Clinical Microbiology 01/1988; 25(12):2440-2. · 4.23 Impact Factor

Publication Stats

1k Citations
513.09 Total Impact Points

Institutions

  • 1982–2003
    • Centers for Disease Control and Prevention
      • Division of Viral Diseases
      Atlanta, Michigan, United States
  • 1987–1996
    • University of Alaska Fairbanks
      • Institute of Arctic Biology
      Fairbanks, AK, United States
  • 1994
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States
  • 1991
    • U.S. Department of Health and Human Services
      Washington, Washington, D.C., United States
    • Animal and Plant Health Inspection Service
      Buzzards Bay, Massachusetts, United States
  • 1990
    • Queen Saovabha Memorial Institute
      Pathum Wan, Bangkok, Thailand
  • 1985
    • U.S. Fish and Wildlife Service
      Washington, Washington, D.C., United States