Prevalence and transmission of honeybee viruses

Abstract

Transmission mechanisms of six honeybee viruses, including acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Kashmir bee virus (KBV), and sacbrood bee virus (SBV), in honey bee colonies were investigated by reverse transcription-PCR (RT-PCR) methods. The virus status of individual queens was evaluated by examining the presence of viruses in the queens' feces and tissues, including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body. Except for head tissue, all five tissues as well as queen feces were found to be positive for virus infections. When queens in bee colonies were identified as positive for BQCV, DWV, CBPV, KBV, and SBV, the same viruses were detected in their offspring, including eggs, larvae, and adult workers. On the other hand, when queens were found positive for only two viruses, BQCV and DWV, only these two viruses were detected in their offspring. The presence of viruses in the tissue of ovaries and the detection of the same viruses in queens' eggs and young larvae suggest vertical transmission of viruses from queens to offspring. To our knowledge, this is the first evidence of vertical transmission of viruses in honeybee colonies.

FIG. 1.

Semiquantification of bee viruses in tissues of queens. (A to E, top panels) RT-PCR results on tissues of queens for the presence of bee viruses. Six tissues including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body (E. body) were examined for the presence of viruses. Primer pairs specific for five viruses including BQCV, CBPV, DWV, KBV, SBV, and an internal control, β-actin, were used separately to amplify RT-PCR products of 700 bp, 455 bp, 702 bp, 415 bp, 824 bp, and 357 bp, respectively. Negative (H₂O [N]) and positive (P) controls (previously identified positive sample) were included in each run of the RT-PCR. (A to E, bottom panels) Densitometric analyses. The y axis depicts the ratio of band intensity of the virus-specific RT-PCR products to that of β-actin RT-PCR products. Results are expressed as mean ± standard deviation (n = 3). Different letters indicate a significant difference among tissues (P = 0.05). (A) Semiquantification of DWV in tissues of queens. (B) Semiquantification of BQCV in tissues of queens. (C) Semiquantification of SBV in tissues of queens. (D) Semiquantification of CBPV bee viruses in tissues of queens. (E) Semiquantification of KBV bee viruses in tissues of queens.

FIG. 1.

Semiquantification of bee viruses in tissues of queens. (A to E, top panels) RT-PCR results on tissues of queens for the presence of bee viruses. Six tissues including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body (E. body) were examined for the presence of viruses. Primer pairs specific for five viruses including BQCV, CBPV, DWV, KBV, SBV, and an internal control, β-actin, were used separately to amplify RT-PCR products of 700 bp, 455 bp, 702 bp, 415 bp, 824 bp, and 357 bp, respectively. Negative (H₂O [N]) and positive (P) controls (previously identified positive sample) were included in each run of the RT-PCR. (A to E, bottom panels) Densitometric analyses. The y axis depicts the ratio of band intensity of the virus-specific RT-PCR products to that of β-actin RT-PCR products. Results are expressed as mean ± standard deviation (n = 3). Different letters indicate a significant difference among tissues (P = 0.05). (A) Semiquantification of DWV in tissues of queens. (B) Semiquantification of BQCV in tissues of queens. (C) Semiquantification of SBV in tissues of queens. (D) Semiquantification of CBPV bee viruses in tissues of queens. (E) Semiquantification of KBV bee viruses in tissues of queens.

FIG. 1.

Semiquantification of bee viruses in tissues of queens. (A to E, top panels) RT-PCR results on tissues of queens for the presence of bee viruses. Six tissues including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body (E. body) were examined for the presence of viruses. Primer pairs specific for five viruses including BQCV, CBPV, DWV, KBV, SBV, and an internal control, β-actin, were used separately to amplify RT-PCR products of 700 bp, 455 bp, 702 bp, 415 bp, 824 bp, and 357 bp, respectively. Negative (H₂O [N]) and positive (P) controls (previously identified positive sample) were included in each run of the RT-PCR. (A to E, bottom panels) Densitometric analyses. The y axis depicts the ratio of band intensity of the virus-specific RT-PCR products to that of β-actin RT-PCR products. Results are expressed as mean ± standard deviation (n = 3). Different letters indicate a significant difference among tissues (P = 0.05). (A) Semiquantification of DWV in tissues of queens. (B) Semiquantification of BQCV in tissues of queens. (C) Semiquantification of SBV in tissues of queens. (D) Semiquantification of CBPV bee viruses in tissues of queens. (E) Semiquantification of KBV bee viruses in tissues of queens.

FIG. 1.

Semiquantification of bee viruses in tissues of queens. (A to E, top panels) RT-PCR results on tissues of queens for the presence of bee viruses. Six tissues including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body (E. body) were examined for the presence of viruses. Primer pairs specific for five viruses including BQCV, CBPV, DWV, KBV, SBV, and an internal control, β-actin, were used separately to amplify RT-PCR products of 700 bp, 455 bp, 702 bp, 415 bp, 824 bp, and 357 bp, respectively. Negative (H₂O [N]) and positive (P) controls (previously identified positive sample) were included in each run of the RT-PCR. (A to E, bottom panels) Densitometric analyses. The y axis depicts the ratio of band intensity of the virus-specific RT-PCR products to that of β-actin RT-PCR products. Results are expressed as mean ± standard deviation (n = 3). Different letters indicate a significant difference among tissues (P = 0.05). (A) Semiquantification of DWV in tissues of queens. (B) Semiquantification of BQCV in tissues of queens. (C) Semiquantification of SBV in tissues of queens. (D) Semiquantification of CBPV bee viruses in tissues of queens. (E) Semiquantification of KBV bee viruses in tissues of queens.

FIG. 1.

Semiquantification of bee viruses in tissues of queens. (A to E, top panels) RT-PCR results on tissues of queens for the presence of bee viruses. Six tissues including hemolymph, gut, ovaries, spermatheca, head, and eviscerated body (E. body) were examined for the presence of viruses. Primer pairs specific for five viruses including BQCV, CBPV, DWV, KBV, SBV, and an internal control, β-actin, were used separately to amplify RT-PCR products of 700 bp, 455 bp, 702 bp, 415 bp, 824 bp, and 357 bp, respectively. Negative (H₂O [N]) and positive (P) controls (previously identified positive sample) were included in each run of the RT-PCR. (A to E, bottom panels) Densitometric analyses. The y axis depicts the ratio of band intensity of the virus-specific RT-PCR products to that of β-actin RT-PCR products. Results are expressed as mean ± standard deviation (n = 3). Different letters indicate a significant difference among tissues (P = 0.05). (A) Semiquantification of DWV in tissues of queens. (B) Semiquantification of BQCV in tissues of queens. (C) Semiquantification of SBV in tissues of queens. (D) Semiquantification of CBPV bee viruses in tissues of queens. (E) Semiquantification of KBV bee viruses in tissues of queens.