Immune interference in the setting of same-day administration of two similar inactivated alphavirus vaccines: eastern equine and western equine encephalitis.

We compared the effect on primary vaccination plaque-reduction neutralization 80% titers (PRNT80) responses of same-day administration (at different injection sites) of two similar investigational inactivated alphavirus vaccines, eastern equine encephalitis (EEE) vaccine (TSI-GSD 104) and western equine encephalitis (WEE) vaccine (TSI-GSD 210) to separate administration. Overall, primary response rate for EEE vaccine was 524/796 (66%) and overall primary response rate for WEE vaccine was 291/695 (42%). EEE vaccine same-day administration yielded a 59% response rate and a responder geometric mean titer (GMT)=89 while separate administration yielded a response rate of 69% and a responder GMT=119. WEE vaccine same-day administration yielded a 30% response rate and a responder GMT=53 while separate administration yielded a response rate of 54% and a responder GMT=79. EEE response rates for same-day administration (group A) vs. non-same-day administration (group B) were significantly affected by gender. A logistic regression model predicting response to EEE comparing group B to group A for females yielded an OR=4.10 (95% CL 1.97-8.55; p=.0002) and for males yielded an OR=1.25 (95% CL 0.76-2.07; p=.3768). WEE response rates for same-day administration vs. non-same-day administration were independent of gender. A logistic regression model predicting response to WEE comparing group B to group A yielded an OR=2.14 (95% CL 1.22-3.73; p=.0077). We report immune interference occurring with same-day administration of two completely separate formalin inactivated viral vaccines in humans. These findings combined with the findings of others regarding immune interference would argue for a renewed emphasis on studying the immunological mechanisms of induction of inactivated viral vaccine protection.

Immunogenicity of an inactivated Japanese encephalitis vaccine (JE-VAX) in humans over 20 years at USAMRIID: using PRNT50 as an endpoint for immunogenicity.

Two hundred and ninety-three subjects received a three-dose primary JE-VAX series and had post-primary shot 3 titers within 56 days at USAMRIID from 1985 to 2005. Overall, the PRNT50 primary response rate (titer of 1:10 or greater) was 269/293 (92%). Eighteen out of 19 subjects (95%) responded with adequate PRNT50 titer within 56 days after first JE-VAX boost. Primary PRNT50 responses to JE-VAX varied significantly in response rates and in geometric means (GMT) by vaccine lot. We recommend that future vaccine studies using PRNT as an immunologic endpoint include a coefficient of variation result alongside the GMT to assist in evaluating GMT results. For subjects who responded within 56 days of primary shot 3, 50% experienced a PRNT50 decline in titer to <1:10 at 805 days and a PRNT80 decline in titer to <1:10 at 355 days. Consequently, for individuals traveling to JE endemic areas, we recommend JE-VAX boost every 2 years and for individuals working with high titers of JE virus in the lab setting, we would recommend JE-VAX boost annually.

Immune interference after sequential alphavirus vaccine vaccinations.

We compared the effect of order of administration of investigational alphavirus vaccines on neutralizing antibody response. Volunteers who received the inactivated eastern and western equine encephalitis (EEE and WEE) vaccines before live attenuated Venezuelan (VEE) vaccine had significantly lower rates of antibody response than those receiving VEE vaccine before EEE and WEE vaccines (66.7% vs. 80.6%; p=0.026). The odds of having a VEE antibody non-response among those initially receiving EEE and WEE vaccines, adjusted for gender, were significant (odds ratio [OR]=2.20; 95% CI=1.2-4.1 [p=0.0145]) as were the odds of non-response among females adjusted for group (OR=1.81; 95% CI=1.2-2.7 [p=0.0037]). Antibody interference and gender effect have major implications for vaccine strategy among those receiving multiple alphavirus vaccines and those developing next generation vaccines for these threats.

Experience with intravenous ribavirin in the treatment of hemorrhagic fever with renal syndrome in Korea.

Results of a clinical study using intravenous (IV) ribavirin for treating Department of Defense personnel with hemorrhagic fever with renal syndrome (HFRS) acquired in Korea from 1987 to 2005 were reviewed to determine the clinical course of HFRS treated with IV ribavirin. A total of 38 individuals enrolled in the study had subsequent serological confirmation of HFRS. Four of the 38 individuals received three or fewer doses of ribavirin and were excluded from treatment analysis. Of the remaining 34 individuals, oliguria was present in one individual at treatment initiation; none of the remaining 33 subjects developed oliguria or required dialysis. The mean peak serum creatinine was 3.46 mg/dl and occurred on day 2 of ribavirin therapy. Both the peak serum creatinine and the onset of polyuria occurred on mean day 6.8 of illness. Reversible hemolytic anemia was the main adverse event of ribavirin, with a >or=25% decrease in hematocrit observed in 26/34 (76.5%) individuals. While inability to adjust for all baseline variables prevents comparison to historical cohorts in Korea where oliguria has been reported in 39-69% cases and dialysis required in approximately 40% HFRS cases caused by Hantaan virus, the occurrence of 3% oliguria and 0% dialysis requirement in the treatment cohort is supportive of a previous placebo-controlled HFRS trial in China where IV ribavirin given early resulted in decreased occurrence of oliguria and decreased severity of renal insufficiency.

Whole-body plethysmography in African green monkeys (Chlorocebus aethiops) with and without jackets.

Indwelling central venous catheters are often used to facilitate frequent phlebotomy while minimizing stress and anesthetic effects on animals. However, nonhuman primates with central venous catheters must wear protective jackets. Jackets routinely are removed for aerosol exposure to agents and respiratory measurements by whole-body plethysmography (WBP) because of the potentially confounding effects of jackets on these procedures. However, removing the jacket may dislodge the catheter, making it unusable. Using each animal as its own control, we tested 12 African green monkeys to determine whether minute volume, tidal volume, respiratory rate, or accumulated volume measurements by WBP differed depending on whether the animal wore a protective jacket or not. We found no statistical differences in any measured respiratory parameter and concluded that the jackets could be left in place on the animal while undergoing plethysmography without compromising the calculations for determining the inhaled dose of aerosolized agent. In addition, this study revealed no obvious contraindications to leaving the jacket in place in other nonhuman primate species, provided that the jacket fits appropriately and that plethysmography is performed correctly.

Monoclonal antibodies passively protect BALB/c mice against Burkholderia mallei aerosol challenge.

Glanders is a debilitating disease with no vaccine available. Murine monoclonal antibodies were produced against Burkholderia mallei, the etiologic agent of glanders, and were shown to be effective in passively protecting mice against a lethal aerosol challenge. The antibodies appeared to target lipopolysaccharide. Humoral antibodies may be important for immune protection against B. mallei infection.

Long-term health effects of repeated exposure to multiple vaccines.

The health of 155 former workers in a US military research program who had received multiple vaccines and 265 matched community controls was assessed. The study population was mostly male (83%) and elderly (median age, 69 years). Multiply immunized (MIP) subjects received vaccines and/or skin tests (median = 154) over a median of 17.3 years; interval from start of immunizations to survey completion was 15-55 years (mean = 43.1 years). MIP subjects characterized themselves as slightly less healthy than controls (P = 0.057). Fatigue (but no other symptom) was reported more frequently in the MIP group (P = 0.011), but was not associated with number of injections, number of vaccines, or time in program. No differences between MIP and control groups were seen for numerous self-reported medical conditions. Several statistically significant abnormalities were seen in clinical laboratory tests among MIP subjects, but none appeared to be clinically significant. A significant difference in frequency of monoclonal spikes and/or paraprotein peaks between MIP (12.5%) and control (4.5%) groups (RR = 2.7, P < 0.003) was observed; no associations with lifestyle, vaccine exposure, or medical conditions were found.

A microtiter fluorometric assay to detect the germination of Bacillus anthracis spores and the germination inhibitory effects of antibodies.

Bacillus anthracis spore germination is usually detected in vitro by alterations in spore refractility, heat resistance, and stainability. We developed a more quantitative, sensitive, and semi-automated procedure for detecting germination by using a microtiter kinetic reader for fluorescence spectrophotometry. The procedure was based on the increase in fluorescence of spores with time during their incubation in germination medium containing a fluorescent nucleic acid-binding dye which stained germinated B. anthracis but not ungerminated (UG) spores. Spore germination in the presence of several germinants was characterized. Although L-alanine and inosine alone stimulated rapid germination in this assay, a medium containing optimal concentrations of L-alanine, adenosine, and casamino acids gave low background fluorescence, stimulated germination completely, and at a reasonable rate. Suspensions of heat-activated, UG spores of B. anthracis strain Ames were preincubated with antibodies (Abs) against whole spores to assess their effect on germination. Analyses of the germination data obtained revealed significant differences between spores pretreated with these Abs and those treated with non-immune sera or IgG. Germination inhibitory activity (GIA) was detected for several polyclonal rabbit anti-spore Ab preparations. These included anti-Ames strain spore antisera, IgG purified from the latter, and spore affinity-purified Abs from antisera elicited against four strains of B. anthracis. Abs elicited against UG as well as completely germinated Ames spores inhibited germination. Abs were ranked according to their GIA, and those specific for UG spores usually exhibited greater GIA. Direct binding to spores of these Abs was detected by an ELISA with whole un-germinated Ames spores. Although specific binding to spores by the anti-spore Abs was shown, their titers did not correlate with their GIA levels. Current efforts are focused on identifying the spore antigens recognized by the anti-spore Abs, characterizing the role of these targeted antigens in disease pathogenesis, and evaluating the ability of specific anti-spore Abs to protect against infection with B. anthracis.

Generation of protective immunity by inactivated recombinant staphylococcal enterotoxin B vaccine in nonhuman primates and identification of correlates of immunity.

At this time there are no vaccines or therapeutics to protect against staphylococcal enterotoxin B (SEB) exposure. Here, we report vaccine efficacy of an attenuated SEB in a nonhuman primate model following lethal aerosol challenge and identify several biomarkers of protective immunity. Initial in vitro results indicated that the mutation of key amino acid residues in the major histocompatibility complex (MHC) class II binding sites of SEB produced a nontoxic form of SEB, which had little to no detectable binding to MHC class II molecules, and lacked T-cell stimulatory activities. When examined in a mouse model, we found that the attenuated SEB retained antigenic structures and elicited protective immune responses against wild-type SEB challenge. Subsequently, a vaccine regimen against SEB in a nonhuman primate model was partially optimized, and investigations of immune biomarkers as indicators of protection were performed. SEB-naïve rhesus monkeys were vaccinated two or three times with 5 or 20 microg of the attenuated SEB and challenged by aerosol with wild-type SEB toxin. Unlike exposure to the native toxin, the vaccine did not trigger the release of inflammatory cytokines (TNF alpha, IL6, or IFN gamma). All rhesus monkeys that developed anti-SEB serum titers > or = 10(4) and elicited high levels of neutralizing antibody survived the aerosol challenge. These findings suggest that the attenuated SEB is fully protective against aerosolized toxin when administered to unprimed subjects. Moreover, experiments presented in this study identified various biomarkers that showed substantial promise as correlates of immunity and surrogate endpoints for assessing in vivo biological responses in primates, and possibly in humans, to vaccines against SEs.

Correlation of body temperature with protection against staphylococcal enterotoxin B exposure and use in determining vaccine dose-schedule.

The immunoprotective potential of a recombinant vaccine against the incapacitating effect of aerosolized staphylococcal enterotoxin B (SEB) in nonhuman primates is reported. SEB belongs to a family of structurally related superantigens responsible for serious, life threatening pathologies. Injecting the recombinant SEB vaccine did not induce temperature elevation in rhesus monkeys, a classical symptom of toxic-shock syndrome. No temperature elevation was noted following injection with control tetanus toxoid. In addition to 100% survival, we observed a clear correlation between vaccine dose and mitigation of temperature elevation after a lethal SEB aerosol challenge. We conclude that the recombinant SEB vaccine is non-pyrogenic and that monitoring changes in body temperature is an important biomarker of toxic shock in a primate animal model.

A comparison of body temperature changes due to the administration of ketamine-acepromazine and tiletamine-zolazepam anesthetics in cynomolgus macaques.

Two commonly used anesthetic combinations, ketamine acepromazine and tiletamine-zolazepam, were compared to identify their effects upon body temperature in cynomolgus macaques. We allocated 30 cynomolgus macaques previously implanted with subcutaneous telemetry devices into two groups of 15 animals. Baseline temperature data were collected for 3 days before administering anesthesia to establish normal diurnal temperature patterns for each monkey. Each group then was anesthetized with either ketamine-acepromazine or tiletamine-zolazepam, and their body temperatures were recorded at 15-min intervals. Both groups had marked decreases in body temperature, with the greatest decreases in the tiletamine-zolazepam group. In addition, both groups had notable post-anesthesia elevations in body temperature that often lasted for more than 24 h postinduction.