Group Title: Clinical and Molecular Allergy 2005, 3:1
Title: Allergens of the entomopathogenic fungus Beauveria bassiana
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Title: Allergens of the entomopathogenic fungus Beauveria bassiana
Series Title: Clinical and Molecular Allergy 2005, 3:1
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Creator: Westwood GS
Huang SW
Keyhani NO
Publication Date: 38363
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Source Institution: University of Florida
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Clinical and Molecular Allergy E



Research

Allergens of the entomopathogenic fungus Beauveria bassiana
Greg S Westwood', Shih-Wen Huang2 and Nemat O Keyhani*1


ed Central

......ce


Address: 'Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA and 2Department of Pediatrics,
University of Florida, College of Medicine, 32610, USA
Email: Greg S Westwood gregwest@ufl.edu; Shih-Wen Huang huangsw@peds.ufl.edu; Nemat O Keyhani* keyhani@ufl.edu
* Corresponding author


Published: II J anuary 2005
Clinical and Molecular Allergy 2005, 3:1 doi:10.1 186/1476-796 1-3-


Received: 16 November 2004
Accepted: I I January 2005


This article is available from: http://www.clinicalmolecularallergy.com/content/3/I/I
2005 Westwood et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.



Abstract
Background: Beauveria bassiana is an important entomopathogenic fungus currently under
development as a bio-control agent for a variety of insect pests. Although reported to be non-toxic
to vertebrates, the potential allergenicity of Beauveria species has not been widely studied.
Methods: IgE-reactivity studies were performed using sera from patients displaying mould
hypersensitivity by immunoblot and immunoblot inhibition. Skin reactivity to B. bassiana extracts
was measured using intradermal skin testing.
Results: Immunoblots of fungal extracts with pooled as well as individual sera showed a
distribution of IgE reactive proteins present in B. bassiana crude extracts. Proteinase K digestion of
extracts resulted in loss of IgE reactive epitopes, whereas EndoH and PNGaseF (glycosidase)
treatments resulted in minor changes in IgE reactive banding patterns as determined by Western
blots. Immunoblot inhibitions experiments showed complete loss of IgE-binding using self protein,
and partial inhibition using extracts from common allergenic fungi including; Alternaria alternate,
Aspergillus fumigatus, Cladosporium herbarum, Candida albicans, Epicoccum purpurascens, and Penicillium
notatum. Several proteins including a strongly reactive band with an approximate molecular mass
of 35 kDa was uninhibited by any of the tested extracts, and may represent B. bassiana specific
allergens. Intradermal skin testing confirmed the in vitro results, demonstrating allergenic reactions
in a number of individuals, including those who have had occupational exposure to B. bassiana.
Conclusions: Beauveria bassiana possesses numerous IgE reactive proteins, some of which are
cross-reactive among allergens from other fungi. A strongly reactive potential B. bassiana specific
allergen (35 kDa) was identified. Intradermal skin testing confirmed the allergenic potential of B.
bassiana.


Background
Microorganisms are currently under intensive study for
use as biopesticides [1-3]. Several fungal species including
Metarhizium anisopliae, Verticillium lecanii, and Beauveria
bassiana are being used as biocontrol agents for a number
of crop, livestock, and human nuisance pests [4-7]. Strains
of B. bassiana have been licensed for commercial use


against whiteflies, aphids, thrips, and numerous other
insect and arthropod pests. B. bassiana fungal formula-
tions are being spread onto a range of vegetables, melons,
tree fruits and nuts, as well as organic crops. As alterna-
tives to chemical pesticides these agents are natural occur-
ring and are considered to be non-pathogenic to humans,


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Clinical and Molecular Allergy 2005, 3:1


although a few cases of B. bassiana mediated tissue infec-
tions have been reported [8,9].

Airborne mold spores are widespread, and many have
been identified as inhalant allergens eliciting type I hyper-
sensitive reactions in atopic individuals [10-14]. Com-
mon allergenic moulds include the anamorphs of
ascomycetes and constitute many species within the Alter-
naria, Aspergillus, and Cladosporium genera [15-19]. The
genes encoding for numerous fungal allergens have been
isolated, and their protein products expressed and charac-
terized. Purified fungal allergens have been shown to be
bound by human IgEs and to elicit allergic reactions in
atopic individuals using skin prick tests. Patients with
mould allergies often display IgE-mediated responses to
multiple fungi, a phenomenon typically thought to result
from the presence of common cross-reactive allergen(s)
[15,20-22], although parallel independent sensitization
to multiple fungal allergens can also occur. In this regards,
identification of genus and/or species specific allergens
would provide useful tools in differentiating allergic reac-
tions due to primary sensitization and those mediated by
cross-reactive epitopes.

In the present study, we demonstrate Beauveria bassiana
crude extracts contain numerous allergens capable of
being recognized by human serum IgEs. The allergens
were proteinaceous in nature, and immunoblot inhibi-
tion experiments revealed the presence of shared epitopes
between Beauveria and several other common fungal
moulds. Potential Beauveria-specific allergens were also
identified, including a strongly reactive ~35-kDa protein
band. Intradermal skin testing using B. bassiana extracts
resulted in allergenic reactions in several individuals,
including some who have had occupational exposure to
the fungus.

Methods
Strains and cultures
Beauveria bassiana (ATCC 90517) was grown on Sabour-
aud dextrose + 0.5-1% yeast extract or Potato dextrose
(PD) media on either agar plates or in liquid broth. Plates
were incubated at 260C for 10-12 days and conidia were
harvested by flooding the plate with sterile dHO2 contain-
ing 0.01% Tween-20. Liquid cultures were inoculated
with conidia harvested from plates at 0.5-1 x 105 conidia/
ml.

Extract preparation
Alternaria alternate, Aspergillus fumigatus, Candida albicans,
Cladosporium herbarum, Epicoccum purpurascens, and Peni-
cillium notatum were acquired from Greer Laboratories
inc., (Lenoir, NC). Extracts were resuspended in TE (40
mM Tris-HC1, pH 8.0, 1 mM EDTA) to a final concentra-
tion of 2 mg/ml. Beauveria bassiana was grown in Sabour-


http://www.clinicalmolecularallergy.com/content/3/1/1



aud's broth containing 1% yeast extract with aeration at
25 C for 3-5 d. Cellular mass was harvested by centrifu-
gation (10,000 x g, 10 min) and freeze-dried. Cells were
resuspended in TE containing 0.1% phenylmethylsulfo-
nyl fluoride (PMSF) and homogenized using a bead-
beater apparatus.

Precipitations
Crude extracts of B. bassiana were subjected to three suc-
cessive precipitations before use in Western blots.

Acetone precipitation
Homogenized B. bassiana extracts (50 ml) were mixed
with 8 x volume (400 ml) of acetone (kept at -20 C), with
rapid stirring, and incubated overnight at -20 C. The pre-
cipitate was collected by centrifugation (30 min, 4000 x
g), and the pellet was air dried (10 min) before being
resuspended in TE containing 0.1% PMSF.

Streptomycin precipitation (removal ofDNA)
Streptomycin sulfate (5 ml of 10% solution) was added
dropwise to resuspended acetone precipitated extracts (40
ml) at 4 C with rapid stirring. Samples were incubated for
an additional 30 min on ice before being centrifuged (15
min, 10,000 x g) in order to remove the precipitate. Pro-
teins in the resultant supernatant were precipitated using
ammonium sulfate.

Ammonium sulfate
The proteins present in the streptomycin sulfate treated
supernatant were precipitated using ammonium sulfate
(75%, final concentration). Saturated ammonium sulfate
(120 ml) was added dropwise to the Beauveria extract (40
ml) at 4 C with rapid stirring. The solution was allowed
to stir overnight at 40C and precipitated proteins were
harvested by centrifugation (30 min, 100,000 x g). The
protein pellet was resuspended in TE containing 0.1%
PMSF (40 ml) and extensively dialyzed against the same
buffer before use.

SDS-Polyacrylamide gel electrophoresis (PAGE)
Protein samples (30-40 Gg) were analyzed by sodium-
dodecyl-sulphate-polyacrylaminde gel electrophoresis
(SDS-PAGE, 10% Bis-tris gel, Invitrogen, Carlsbad, CA)
using standard protocols. Gels were stained with Gelcode
blue stain reagent (Pierce, Rockford, IL) and subsequently
de-stained with dH20.

Western blotting
Protein samples were separated under reducing condi-
tions using 10% Bis-tris polyacrylamide gels (Invitrogen
Mops system) and transferred to polyvinylidene-fluoride
(PVDF) membranes (Invitrogen) as described. Immunob-
lot experiments were performed using individual and
pooled human sera as the primary antibody solution as


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indicated. Typically, sera were diluted 1:5 with Tris-HCl
buffered saline (TBS) containing 5% dry milk + 0.1%
Tween-20. IgE-specific reactivity was visualized using a
horseradish peroxidase (HRP) conjugated goat anti-
human IgE polyclonall) secondary antibody (BioSource
International, Los Angeles, CA). Membranes were washed
with TBS containing 0.1% Tween-20 and bands were vis-
ualized using the Immuno-Star HRP detection system
(Biorad, Hercules, CA).

Enzyme Treatments
The ammonium sulfate fraction of B. bassiana crude
extracts was treated with Proteinase K (ICN-Biomed,
Aurora, Oh) following standard protocols. Typically, sam-
ples (36 il) were incubated with 4 jl Proteinase K solu-
tion (10 mg/ml in 50 mM Tris-HC1, pH 7.5) for 2 hr at
37C before analysis. Samples were also treated with
endoglycosidase-H (EndoH, New England Biolabs, Bev-
erly, MA) and peptide: N-Glycosidase F (PNGaseF, New
England Biolabs) according to the manufacturer's recom-
mendations. For EndoH and PNGaseF treatments, sam-
ples (36 jil) were denatured in 4 jil 10 x denaturing buffer
(0.5% SDS, 1% B-mercaptoethanol) at 1000C for 10 min
prior to the addition of the EndoH (5 jil of 10 x G5 Reac-
tion Buffer, 50 mM sodium citrate, pH 5.5) and PNGaseF
reaction buffers (50 mM sodium phosphate pH 7.5) and
enzymes (5 jil), respectively. Reactions were incubated at
37C for 2 h before being analyzed by SDS-PAGE and
Western blotting.

Immunoblot inhibition
IgE binding to B. bassiana proteins were competed with
proteins of other fungal extracts. SDS-PAGE resolved B.
bassiana proteins were electroblotted to PVDF membranes
as described above. Membranes were blocked with TBS
containing 5% dry milk + 0.1% Tween-20 and strips were
incubated with pooled human sera (1:5 v/v in same
buffer) containing 100-500 jig of the indicated fungal
crude protein extract.

Skin sensitivity profiles to fungal extracts
Patients were tested with 9 common fungal extracts for
allergy diagnosis using a skin prick assay. The following
extracts were obtained from ALA-Abello (Round Rock,
TX); Alternaria tenius, Aspergillus fumigatus, Cephalosporium
(Acremonium strictum), Curvularia spp. Bipolaris, Epicoccum
nigram, Fusarium spp., Helminthosporium sativum, Hor-
modendrum horde, Penicillium (mixed, P. chrysogenum and
P. notatum). Extracts were tested using a 1:10 dilution of
the 20,000 PNU/ml stock solution, and skin sensitivity
was recorded on a relative scale from 0-4 reflecting the
size of induration or weal (4 representing the highest reac-
tivity) and using histamine (0.1 mg/ml) reaction scored as
a 3 if no interference was present.


AB


I


MW
(kDa) 1 2 3 4


191
97
97 ...

64

51


39


28


5 6


Figure I
SDS-PAGE and immunoblot analysis of Beauveria bassiana
crude extracts. SDS-PAGE, Gelcode blue stained, lanes A) 5
jig protein standards, and B) 40 jig B. bassiana crude extract.
Immunoblots probed with pooled serum mix-I (patients dis-
playing mould allergies), lanes I), 5 pig protein standards, 2)
20 jig B. bassiana crude extract, 3) 40 jig crude extract, 4) 40
jig crude extract, Proteinase K treated, 5) 40 jig crude
extract, denaturing buffer control (no EndoH), 6) 40 ipg
crude extract, EndoH treated




Intradermal skin testing
B. bassiana crude extracts were prepared as described
above but were extensively dialyzed against 0.15 N NaCl
and filtered through a 0.22 jim filter before use. Subjects
were given intradermal injections of 0.1 ml crude extract
ranging in concentration from 0.01-1 mg/ml. Control
injections included saline and histamine (0.1 mg/ml).
Allergenic reactions were allowed to develop for 15-30
min before the height and width of the reactions were
recorded.

Results
Identification of IgE reactive bands
An ammonium sulfate fraction of B. bassiana proteins was
resolved on SDS-PAGE (Fig. 1, lane B) and transferred to
PVDF membranes as described in the Materials and Meth-
ods. Membranes were probed with sera from individual
patients who were reactive to various moulds (Table 1),
which was pooled and used to demonstrate IgE reactivity
against antigens present in B. bassiana extracts (Fig. 1).
Serum mix-I represents pooled sera derived from patients
E, J, K, L, and M, as well as three additional patients that


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Table I: Allergic profile of patients A-G, obtained by skin prick testing.


Individual Skin Reactivity to Fungal Extracts*


Altt Asp Cep Cur Epi Fusa


Helmin Hormo


*Skin test scores were registered using a relative scale from 0-4 with 4 representing the highest reactivity as described in the Materials and
Methods. tAbbreviations used; Alt, Alternaria tenius; Asp, Aspergillus fumigatus; Cep, Cephalosporium (Acremonium strictum); Cur, Curvularia spp. Bipolaris;
Epi, Epicoccum nigram; Fusa, Fusarium spp.; Helmin, Helminthosporium sativum; Hormo, Hormodendrum horde; Pen, Penicillium (mixed, P. chrysogenum and
P. notatum).


were only tested (skin prick) against Aspergillus and Peni-
cillium, displaying test scores of 3-4 for each. These data
demonstrate human IgE binding of allergens present in B.
bassiana extracts. Initial blots showed 12-15 distinct reac-
tive protein bands, ranging in molecular mass from 12
kDa to >95 kDa (under denaturing conditions); with the
most prominent bands located around 64, 45, and 35
kDa. Control experiments omitting either the primary or
secondary antibody incubation steps resulted in complete
loss of signal. Proteinase K digestion of samples also
resulted in loss of all signal (Fig. 1, lane 4), indicating the
proteinaceous nature of the IgE reactive bands. Since the
carbohydrate moieties of several protein allergens are
known to play a role in their allergenicity and even cross-
reactivity [20-22], samples were treated with the deglyoc-
osylating enzymes EndoH and PNGaseF. Control experi-
ments incubating samples in the EndoH denaturing
buffer without any enzyme altered the IgE-reactive signals
(Fig. 1, lane 5), however, samples treated with EndoH did
not appear any different than control reactions (Fig. 1,
lane 6). Similar results were obtained in PNGaseF digests
(data not shown). These data appear to indicate that the
B. bassiana IgE-antigen profiles observed on Western blots
are proteins with minimal contributions due to
glycosylation.

Immunoprint Analysis of B. bassiana: Reactivity with
Individual Sera
In order to determine the variation and distribution of
serum IgEs reactive to B. bassiana extracts, individual sera
from patients displaying mould allergies (Fig. 2, lanes A-
G) as well as random sera from the general population
(Fig. 2, lanes H-M) were used as probes for Western blots
(Fig. 2). The reactivity of pooled sera from patients A-G


MD1 A B C D E
(kDa)






39-! 1

I I
^c| ^ !


ZS r


F G 2 H I JKLM

A




,, --


I I


-g


Figure 2
Immunoprint analysis of B. bassiana extracts (40 pg crude
extract/strip) probed with individual sera. Lane I) 5 pg pro-
tein standards, 2) pooled serum mix-11 (patients displaying
mould allergies). Lanes A)-G) membrane strips treated with
individual sera, Lanes H)-M) membrane strips probed with
individuals having had occupational exposure to B. bassiana
and other fungi (see intra-dermal skin test results for individ-
uals J-M, Table 2).


(termed serum mix-II) is also shown (Fig. 2, lane 2). Skin
prick test results for patients A-G are shown for compara-
tive purposes (Table 1) and represent the clinically deter-
mined reactivity of each patient to extracts of the tested
fungal species. Patients (A-G) were selected based skin


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Patient ID


Clinical and Molecular Allergy 2005, 3:1


I







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prick reactivity to at least 4 different fungi with scores of 2
or greater. Identical concentrations of B. bassiana extract
(40 jig) were resolved by SDS-PAGE, blotted to PVDF
membranes, and the lanes were cut into separate strips.
Each strip was treated with a 1:5 dilution of each respec-
tive serum as described in the Materials and Methods (Fig.
3, lane 2 is the sera pool). A total of 16 individual sera
were tested, with the sera from three patients displaying
no IgEs reactive to proteins present in the B. bassiana
extracts. The results for the remaining 13 sera are shown
in Fig. 2. The data show a large individual variation in
serum IgEs capable of binding epitopes present in B. bas-
siana extracts, both in terms of banding distribution and
the intensity of the reaction. No correlation was observed
between measurements of total IgE and the observed
binding to B. bassiana allergens. Some patients displayed
strong reactions to multiple bands, whereas others to a
more limited set of epitopes. Distinct strongly reactive
bands ranging from 40 kDa to approximately 200 kDa
could be seen in sera A, E, and to a lesser extent L. A
strongly reactive 35 kDa band was visible in sera C, G, E,
and L. Several sera displayed IgEs that bound to only a
limited set of 2-3 allergens (C, F, G, weak bands in B, I, J,
K, and M). Blots probed with one serum (H) resulted in a
large smear ranging from ~30 kDa to 55 kDa. The reason
for the observed smear is unknown and efforts to distin-
guish separate bands by manipulating the concentrations
of either sera or extract were unsuccessful. A number of
bands (based upon molecular mass) appeared to be com-
mon to several sera including proteins of approximately
35, 42-48, and 60 kDa. A number of allergens of high
molecular weight ( 100-200 kDa) were also visible; how-
ever the resolution in this range on the Western blots is
poor.

Intradermal Skin Testing
A total often individuals were tested for allergenic reactiv-
ity to B. bassiana crude extracts using an intradermal deliv-
ery procedure. Data using 1 mg/ml B. bassiana crude
extract and histamine controls are presented in Table 2.
Seven out of the ten individuals (ID #s, J-0, and Q)
displayed skin reactivity reactions to the B. bassiana
extracts (Table 2, also see corresponding Western blot
results for individuals J, K, L, and M; Fig. 2). It is interest-
ing to note that 4 (J-M) of 5 individuals (plus S) that have
had occupational exposure to B. bassiana displayed skin
reactivity as well as bands on Western blots. A preliminary
correlation was observed between the B. bassiana/hista-
mine ration and the in vitro reactivity of individual sera in
Western blots. Individuals J, K, and M, displayed B.
bassiana/histamine control ratios <1, also showed weak
bands in Western blots (Fig. 2), whereas individual L who
had a B. bassiana/histamine ratio = 1.65, reacted against
numerous epitopes in the extract and with a higher
intensity.


MW
(kDa:

191
97
64
51


39


28


1 I.A A 4 6 '7 R 9 10


Figure 3
IgE immunoblot inhibition with fungi. B. bassiana protein
strips (40 jig crude extract) were blocked and incubated with
mix containing (500 jil) pooled sera (mix-ll) and 2) no addi-
tions, 3) 40 jig Alternaria alternate crude extract, 4) 400 jig
Alternaria alternate, 5) 40 jig Aspergillus fumigatus, 6) 400 jig
Aspergillus fumigatus, 7) 400 [ig Cladosporium herbarum, 8) 400
jig Candida albicans, 9) 400 jig Epicoccum purpurascens, and
10) 400 jig Penicillium notatum protein.



Cross-reactivity among different fungi
In order to determine the extent of cross-reactivity of B.
bassiana allergens with other fungi, immunoblot inhibi-
tion experiments were performed. Identical concentra-
tions ofB. bassiana crude extract (40 jig) were resolved by
SDS-PAGE, blotted to PVDF membranes, and lanes were
cut into separate strips. Each strip was treated with a 1:5
dilution pooled sera (serum mix-II) as the primary anti-
body supplemented with concentrations of fungal crude
extracts as described in the Materials and Methods. Fig. 3
shows Western blots in which the binding of human IgEs
to allergens present in B. bassiana extracts were competed
with: excess crude extracts from Alternaria alternate (Fig 3,
lanes 3, 4), Aspergillus fumigatus (lanes 5, 6), Cladosporium
herbarum (lanes 7), Epicoccum purpurascens (Lane 8), Peni-
cillium notatum (lane 9), and Candida albicans (lane 10).
There was complete loss of all signals using 2-fold excess
B. bassiana extract as the competitor (data not shown).
These data indicate that while Beauveria possess many
epitopes in common with several other fungi, notably
Alternaria and Penicillium, a 35-kDa major reactive band
was not inhibited by any extract tested.

Discussion
Although it is well known that fungi are important triggers
of respiratory allergies, the potential allergenicity of ento-


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Table 2: Intradermal skin test results using B. bassiana extract


Histamine control (0.1 mg/ml)


B. bassiana Extract (I mg/ml)


B. bassiona/Histamine


Erythema2

12 x 13
14 x 13
26 x 28
10 x 12
21 x 17
18 x 21
5x4
10 x 13
I x 13
4x4


Induration ratio3

0.65
0.52
1.65
0.30
0.49
0.21
0.08
0.51
0.07
0.04


Iln all instances saline control injections produced indurations of 3-4 mm x 3-4 mm.
2Values recorded in mm x mm.
31nduration ratio expressed as B. bassiana reaction area (mm2)/histamine reaction area (mm2).
4Individual with occupational exposure to Beauveria bassiona.
5See Western Blot results for individual, Fig. 2.


mopathogenic fungi used in biocontrol has largely been
untested. Aerobiological surveys of conidial fungi and
skin sensitivity tests to fungal extracts performed in the
1980s in the Netherlands revealed that although Beauveria
could barely be detected in airborne samples, and repre-
sented less than 0.1% of the airborne fungal "flora", the
incidence of allergic skin test reaction to Beauveria was the
highest of all fungal species tested [10,23,24]. In rural
areas, the use of fungi in agricultural pest management
practices can greatly increase the potential for human
exposure to these agents. Likewise, in urban settings, the
commercialization of fungal products for household use
may potentiate a much wider problem since indoor air
concentrations of the moulds can greatly increase. For
these reasons, an examination of the allergenic potential
of Beauveria bassiana is imperative.

The present study demonstrated the allergenic potential of
B. bassiana directly by intradermal skin testing of
individuals and in vitro by revealing the presence of serum
IgEs capable of binding allergens present in fungal crude
extracts. Over 20 different IgE binding proteins were
observed using Western blots probed with sera from
patients displaying mould allergies. Results using
individual sera revealed a wide variation in IgE-binding
proteins between sera, although several common bands,
including a protein with an apparent molecular mass of
35 kDa were visible among the sera of several patients.

Our in vitro observations were confirmed by intradermal
skin testing on individuals using B. bassiana extracts.


While the testing sample population was small, these
results indicated that our extracts were able to elicit aller-
gic reactions in individuals, including some that have had
occupational exposure to the fungus. Concentrations of
~1 mg/ml of B. bassiana extracts were required to elicit
indurations equivalent to 0.1 mg/ml histamine in most
individuals, indicating the possibility of potent allergens
in the Beauveria extract. Interestingly, not all individuals
specifically exposed to B. bassiana displayed allergic
reactions and individuals J, K, and M (who did display
mild allergic reactions, Table 2) did not react to the 35
KDa protein based upon Western blotting results (Fig. 2).
We do not, however, have any quantifiable index of expo-
sure for the individuals in our sample and any interpreta-
tions should be made with some caution.

Numerous studies have revealed the presence of cross-
reactive proteins among fungal species between genera
[15,20-22,25-27]. In our experiments, (excess) crude
extract from a test organism was added during the primary
antibody (human sera) incubation. Common or shared
epitopes between B. bassiana and the test fungus would
result in a loss of signal due to competition for reactive
IgEs. However, IgEs reactive to Beauveria-specific allergens
would not be affected, resulting in no change in the corre-
sponding reactive bands on a Western blot. Loss of a sig-
nal would indicate that a homolog or shared epitope (IgE-
reactive) exists between the two fungal species, implying
that primary sensitization by one organism can result in
an allergic reaction when exposed to the homologous
allergen of another organism. Competitive immunoblot


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Patient ID


Induration2


7x6
20 x 15
Ilx 10
15 x 16
16 x 14
21 x 16
15 x 17
15 x 14
15 x 15
20 x 19


Erythema2

12 x 16
55 x 50
16 x 33
36 x 44
38 x 58
39 x 59
44 x 45
36 x 38
55 x 38
38 x 43


Induration2

8x8
13 x 12
13 x 14
10x 12
10 x I
9x8
5x4
9x 12
4x4
4x4


Clinical and Molecular Allergy 2005, 3:1








Clinical and Molecular Allergy 2005, 3:1


inhibition experiments revealed significant epitope
homology between B. bassiana and several clinically
important fungi responsible for IgE-mediated allergic
reactions in atopic individuals. Thus, an allergic reaction
to Beauveria exposure may arise in patients sensitized to
other fungi. Extracts from A. alternate and E. purpurascens
almost completely competed with allergens present in the
B. bassiana extract with the notable exception of the ~35
kDa allergen. Competition experiments using A. fumiga-
tus, C. herbarum, C. albicans, and P. notatum extracts also
indicated the presence of many shared epitopes, although
distinct (non-competed) IgE-binding B. bassiana proteins
of 35 kDa, 64 kDa, and >200 kDa molecular mass were
detectable. These proteins, particularly the 35 kDa aller-
gens may represent B. bassiana specific allergens. Experi-
ments are underway to characterize the 35 kDa allergen,
which may lead to a diagnostic assay for B. bassiana sensi-
tization. Finally, our analysis of potential B. bassiana aller-
gens was limited to cell extracts grown under specific
conditions and did not include the culture filtrate. Extra-
cellular proteases, an important class of fungal proteins
that can elicit allergenic reactions, have been characterized
from a number of fungal species [28-31], and are likely to
be present in B. bassiana. A careful examination of culture
growth conditions is also warranted in order to provide a
standardized reagent for testing purposes.

Conclusions
Although Beauveria holds promise as an arthropod bio-
logical control agent, there have been few reports on the
allergenic potential of these organisms. Identification of
B. bassiana specific allergens can lead diagnostic methods
for determining sensitization to this organism and may
provide a rational basis for allergen attenuation in order
to yield safer biocontrol products. The observed cross-
reactivity among proteins of B. bassiana and the fungi
tested, highlight the importance of considering the possi-
bility that multiple fungal sensitivity can occur due to
exposure to a single fungus. Further testing should be
performed to determine the scope, severity, and range of
allergenic reactions to B. bassiana.

Competing Interests
The authors) declare that they have no competing
interests.

Authors' contributions
GSW carried out the immunoassays and other in vitro
experiments. SWH performed the clinical experiments
and participated in the design of the study. NOK con-
ceived of the study, and participated in its design and
coordination, and drafted the manuscript.


http://www.clinicalmolecularallergy.com/content/3/1/1




Acknowledgements
We would like to thank Ruby Teng and Moya Chin for technical assistance.
This paper is Florida Agricultural Experimental Station Journal series
number R-10187.

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