Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development

Mott, Tiffany M.; Vijayakumar, Sudhamathi; Sbrana, Elena; Endsley, Janice J.; Torres, Alfredo G.

doi:10.1371/journal.pntd.0003863

Cited by 32 publications

(53 citation statements)

References 57 publications

(74 reference statements)

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“…7A). These findings are consistent with previous reports indicating that high Th1 bias antibody titers afford superior protection (109,(130)(131)(132)(133). Our data also underscore a protective role for antibodies of the IgG subclass ( Fig.…”

Section: Discussionsupporting

confidence: 93%

Antibodies against In Vivo -Expressed Antigens Are Sufficient To Protect against Lethal Aerosol Infection with Burkholderia mallei and Burkholderia pseudomallei

et al. 2017

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Burkholderia mallei, a facultative intracellular bacterium and tier 1 biothreat, causes the fatal zoonotic disease glanders. The organism possesses multiple genes encoding autotransporter proteins, which represent important virulence factors and targets for developing countermeasures in pathogenic Gram-negative bacteria. In the present study, we investigated one of these autotransporters, BatA, and demonstrate that it displays lipolytic activity, aids in intracellular survival, is expressed in vivo, elicits production of antibodies during infection, and contributes to pathogenicity in a mouse aerosol challenge model. A mutation in the batA gene of wild-type strain ATCC 23344 was found to be particularly attenuating, as BALB/c mice infected with the equivalent of 80 median lethal doses cleared the organism. This finding prompted us to test the hypothesis that vaccination with the batA mutant strain elicits protective immunity against subsequent infection with wild-type bacteria. We discovered that not only does vaccination provide high levels of protection against lethal aerosol challenge with B. mallei ATCC 23344, it also protects against infection with multiple isolates of the closely related organism and causative agent of melioidosis, Burkholderia pseudomallei. Passive-transfer experiments also revealed that the protective immunity afforded by vaccination with the batA mutant strain is predominantly mediated by IgG antibodies binding to antigens expressed exclusively in vivo. Collectively, our data demonstrate that BatA is a target for developing medical countermeasures and that vaccination with a mutant lacking expression of the protein provides a platform to gain insights regarding mechanisms of protective immunity against B. mallei and B. pseudomallei, including antigen discovery.

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Section: Discussionsupporting

confidence: 93%

Antibodies against In Vivo -Expressed Antigens Are Sufficient To Protect against Lethal Aerosol Infection with Burkholderia mallei and Burkholderia pseudomallei

et al. 2017

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“…Therefore, the incorporation of antibody-inducing proteins is important when designing a subunit vaccine against Burkholderia. Nevertheless, it is currently understood that balanced cellular and humoral immune responses will be required for vaccine-induced protective immunity against B. pseudomallei and B. mallei (29,(36)(37)(38). Interestingly, in the present study, there does not appear to be a direct correlation between antibody titers (anti-LPS or antiprotein) and protection.…”

Section: Use Of Novel Burkholderia Antigens For Nanovaccinescontrasting

confidence: 61%

Use of Reverse Vaccinology in the Design and Construction of Nanoglycoconjugate Vaccines against Burkholderia pseudomallei

Muruato

Tapia

Hatcher

et al. 2017

Clin Vaccine Immunol

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Burkholderia pseudomallei is a Gram-negative, facultative intracellular pathogen that causes the disease melioidosis in humans and other mammals. Respiratory infection with B. pseudomallei leads to a fulminant and often fatal disease. It has previously been shown that glycoconjugate vaccines can provide significant protection against lethal challenge; however, the limited number of known Burkholderia antigens has slowed progress toward vaccine development. The objective of this study was to identify novel antigens and evaluate their protective capacity when incorporated into a nanoglycoconjugate vaccine platform. First, an in silico approach to identify antigens with strong predicted immunogenicity was developed. Protein candidates were screened and ranked according to predicted subcellular localization, transmembrane domains, adhesive properties, and ability to interact with major histocompatibility complex (MHC) class I and class II. From these in silico predictions, we identified seven "high priority" proteins that demonstrated seroreactivity with anti-B. pseudomallei murine sera and convalescent human melioidosis sera, providing validation of our methods. Two novel proteins, together with Hcp1, were linked to lipopolysaccharide (LPS) and incorporated with the surface of a gold nanoparticle (AuNP). Animals receiving AuNP glycoconjugate vaccines generated high proteinand polysaccharide-specific antibody titers. Importantly, immunized animals receiving the AuNP-FlgL-LPS alone or as a combination demonstrated up to 100% survival and reduced lung colonization following a lethal challenge with B. pseudomallei. Together, this study provides a rational approach to vaccine design that can be adapted for other complex pathogens and provides a rationale for further preclinical testing of AuNP glycoconjugate in animal models of infection.KEYWORDS Burkholderia pseudomallei, melioidosis, nanoglycoconjugate, nanovaccine, reverse vaccinology B urkholderia pseudomallei is a Gram-negative aerobic bacterium common to tropical and subtropical climates worldwide. This saprophytic bacterium can survive in soil and water and, upon transmission to humans or other susceptible mammals, cause the disease melioidosis. Human disease can present with a wide variety of clinical manifestations, including cutaneous and soft tissue abscesses, lymphadenopathy, and sepsis (1, 2). Clinical symptoms have been correlated with the route of infection; percutaneous infection often results in a purulent lesion at the site of inoculation, whereas respiratory

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“…challenged with 1.5 ϫ 10 4 CFU of B. mallei strain lux (CSM001) had survival rates of 100% and 75%, respectively. Necropsy and organ CFU enumeration showed that all mice had splenomegaly and splenic abscesses due to TMM001 colonization (16). This study was significant because it revealed the first attenuated strain to provide 100% and 75% survival against B. mallei and B. pseudomallei challenge, respectively.…”

mentioning

confidence: 77%

“…Live attenuated vaccines, the use of which is regarded as the most viable strategy against B. mallei, have been tested with some success (14)(15)(16)(17). Recently, our laboratory evaluated an iron acquisition-deficient B. mallei ⌬tonB (TMM001) strain for use as a live attenuated vaccine in acute inhalational glanders and melioidosis (B. pseudomallei) murine models.…”

mentioning

confidence: 99%

Burkholderia mallei CLH001 Attenuated Vaccine Strain Is Immunogenic and Protects against Acute Respiratory Glanders

et al. 2016

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Burkholderia mallei is the causative agent of glanders, an incapacitating disease with high mortality rates in respiratory cases. Its endemicity and ineffective treatment options emphasize its public health threat and highlight the need for a vaccine. Live attenuated vaccines are considered the most viable vaccine strategy for Burkholderia, but single-gene-deletion mutants have not provided complete protection. In this study, we constructed the select-agent-excluded B. mallei ⌬tonB ⌬hcp1 (CLH001) vaccine strain and investigated its ability to protect against acute respiratory glanders. Here we show that CLH001 is attenuated, safe, and effective at protecting against lethal B. mallei challenge. Intranasal administration of CLH001 to BALB/c and NOD SCID gamma (NSG) mice resulted in complete survival without detectable colonization or abnormal organ histopathology. Additionally, BALB/c mice intranasally immunized with CLH001 in a prime/boost regimen were fully protected against lethal challenge with the B. mallei lux (CSM001) wild-type strain. Burkholderia mallei, the causative agent of glanders, is a Gramnegative, obligate mammalian pathogen. Glanders is primarily a disease of solipeds, with rare cases occurring among humans (1, 2). Naturally acquired human cases occur in areas of endemicity, particularly among those exposed to infected solipeds (2-4). Additionally, cases have been reported among laboratory workers (5, 6). The World Organization for Animal Health coordinates ongoing efforts toward worldwide eradication; however, regional endemicity still exists in Africa, Asia, the Middle East, and South America (2). Recent equid outbreaks in the Middle East and Asia (7-9) set the stage for possible glanders reintroduction into disease-free regions; as a result, glanders has been classified as a reemerging disease.Glanders is a debilitating and often fatal disease transmitted via cutaneous and respiratory routes. Disease course and severity are route dependent, with respiratory cases being the most severe (3). Respiratory infection is characterized by rapid onset of symptoms, including fever, lymphadenopathy, pulmonary abscesses, pneumonia, disseminated organ infection, and, ultimately, septicemia (3, 5, 10). Because of the high incidence of septicemia following respiratory infection, fatality rates in human respiratory cases have been estimated at 90% without treatment and 40% with aggressive antibiotic therapy (11).The use of B. mallei as a biothreat agent has been documented in different world military conflicts (10,12,13). Its amenability to aerosolization, low infectious dose, high case fatality rate, and high-level antibiotic resistance make B. mallei a top candidate for malevolent use (1, 10). Because of its perceived public health threat, the Department of Health and Human Services has categorized B. mallei as a tier 1 select agent. The lack of effective treatments against these bacteria highlights the need for an effective vaccine. Numerous vaccine strategies have been tested; however, to date there are n...

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Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development

Cited by 32 publications

References 57 publications

Antibodies against In Vivo -Expressed Antigens Are Sufficient To Protect against Lethal Aerosol Infection with Burkholderia mallei and Burkholderia pseudomallei

Antibodies against In Vivo -Expressed Antigens Are Sufficient To Protect against Lethal Aerosol Infection with Burkholderia mallei and Burkholderia pseudomallei

Use of Reverse Vaccinology in the Design and Construction of Nanoglycoconjugate Vaccines against Burkholderia pseudomallei

Burkholderia mallei CLH001 Attenuated Vaccine Strain Is Immunogenic and Protects against Acute Respiratory Glanders

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