Brief Communication Serodetection of Dengue virus and its antibodies among blood donors in the western region of Saudi Arabia: a preliminary study Ahmed M. Ashshi Department of Laboratory Medicine, Faculty of Applied Medical Sciences, Umm Al-Qura University, Holy Makkah, Saudi Arabia
Introduction
Dengue is the most important mosquito-borne viral disease in the world and is endemic in more than 100 countries, with an estimated 100 million infected cases and 25,000 deaths per year worldwide1. Dengue virus (DENV) is caused by a single-stranded RNA virus with five serotypes (DENV-1, DENV-2, DENV-3, DENV-4 and DENV-5)1,2 and its clinical picture ranges from relatively mild Dengue fever, to the life-threatening Dengue haemorrhagic fever/Dengue shock syndrome. In Saudi Arabia, an outbreak of Dengue was reported for the first time in Jeddah during the 1990s3. Next, two peaks of infections were reported during 20052006 and another two peaks in 2008. After that, both Dengue disease and its serious haemorrhagic forms became endemic in the Western and Southern regions of the Kingdom4-6. So far, Aedes aegypti remains the mosquito vector most strongly implicated in Dengue transmission and endemicity in this country, although Aedes albopictus is also incriminated6. The potential role of foreign visitors, including pilgrims, who arrive from neighbouring African and Southeast Asia countries with known Dengue endemicity, is also a concern. Millions of visitors come annually from the whole world to the Holy Mecca. Some of these visitors may arrive during their viraemic stage of Dengue infection and, thereby, facilitate the spread of DENV4-6. Emerging infectious diseases still pose threats and risks to the safety of blood products and transfusions. Special attention has recently been paid to the significant role of blood transfusion in the transmission of DENV from asymptomatic infected blood donors to recipients. This form of viral transmission is another source of dissemination and endemicity of the virus in the community7-10. The presence of anti-DENV antibodies is a further important cause of concern in transfusion medicine. It has been proposed that transfusion of blood from donors with circulating non-neutralising or partially neutralising anti-DENV antibodies may increase the susceptibility of recipients to immunological conditions, with these recipients being at a higher risk of haemorrhagic Dengue if they are exposed to a later infection by another DENV serotype within 6 months after the transfusion11. Furthermore, the transmission of
heterotypic anti-DENV antibodies from infected blood donors may enhance viral infectivity in recipients who are later exposed to another DENV serotype11. Given the absence of an approved blood screening test for DENV in Saudi Arabia and in response to the new epidemiological situation, the current pilot study was designed to determine the seroprevalence of DENV infection and/or its antibodies among blood donors in the Holy Mecca in order to improve the safety of the blood supply and products in blood donation services in Saudi Arabia.
Materials and methods
Ethical approval Ethical approval was obtained from Umm Al-Qura Institutional Review Ethics Committee before starting the study and all blood samples were collected after informed, written consent had been given by the participants. Participants, blood sampling and screening This cross-sectional seroprevalence study was conducted at the blood transfusion service in Heraa' General Hospital, Holy Mecca, Saudi Arabia. From January to April 2014, a total of 100 healthy eligible Saudi male blood donors (aged between 25 and 50 years old), who were negative for infections with human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) and who were accepted for blood donation according to the policy set up by the Kingdom of Saudi Arabia Health Ministry, were randomly included. From each enrolled donor, 10 mL of whole venous blood was collected into tubes without anticoagulant. The tubes were centrifuged at 3,000 rpm for 15 minutes to obtain serum. Sera were then stored in a freezer at −20 °C until screened. At the end of the collection phase, the samples of serum were screened for DENV non-structural protein 1 (NS1) antigen, anti-DENV IgM and IgG antibodies using a commercially available Dengue virus Pan-E NS1 early enzyme-linked immunosorbent assay (ELISA), Dengue virus IgM capture ELISA, and Dengue virus IgG capture ELISA, respectively (all from Panbio, Brisbane, Australia). In each assay, all samples were processed in duplicate,
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 © SIMTI Servizi Srl
135
Ashshi AM
according to the manufacturer's instructions, and were repeated again if the results from the duplicate testing were not concordant. Data interpretation According to the manufacturer's recommendations, a positive ELISA result for either DENV-NS1 antigen or anti-DENV IgM antibody was defined as an index value >11 Panbio Units (PU), while a positive ELISA result for anti-DENV IgG antibody was defined as an index value >22 PU. Index values of 9-11 PU for either DENV-NS1 antigen or anti-DENV IgM antibody and index values of 18-22 PU for anti-DENV IgG antibody were considered as equivocal reactions, in accordance with the manufacturer's recommendations.
Results
Transfusion safety is of paramount importance to the recipient of blood products. In recent decades, the safety of blood products with regards to the risk of HIV, HBV and HCV infections has increased dramatically; however, emerging infectious diseases pose new threats to the recipients of blood transfusions8. The risks of transfusion-associated transmission of DENV and/or its antibodies are emerging worldwide9-13. Dengue is an endemic disease in Saudi Arabia, particularly in its Western region3-6, yet there is no approved blood screening test for DENV infection in this country. This aim of this study was to determine, for the first time, the seroprevalance of DENV infection and its antibodies among Saudi blood donors who live in the Holy Mecca. In the present preliminary study, 100 healthy adult male Saudi blood donors, negative for HIV, HCV and HBV infections and accepted for blood donation according to the policy set up by the Kingdom of Saudi Arabia Health Ministry, were screened for DENVNS1 antigen and IgM and IgG anti-DENV antibodies using commercially available ELISA kits (Panbio). As shown in Table I, among the tested donors, 1% showed positivity for DENV-NS1 antigen, 6% were positive for anti-DENV IgM antibody and 7% were positive for anti-DENV IgG antibody. There were also equivocal results for NS1 antigen (1%), IgM antibody (1%), and IgG antibody (1%) (data not shown). Table I - Results of screening for DENV infection among 100 blood donors. Tested blood donors 100
DENV-NS1 positivity* 1 (1%)
Anti-DENV antibody positivity* IgM only
IgG only
IgM + IgG
6 (6%)
7 (7%)
0 (0%)
DENV: Dengue virus; NS1: non-structural protein 1 antigen; IgM: immunoglobulin M antibody; IgG: immunoglobulin G antibody. * Values of DENV-NS1 antigen or anti-DENV IgM antibodies are considered positive when >11 Panbio Units, while values of anti-DENV IgG antibodies considered positive are >22 Panbio Units.
Discussion
The fact that DENV can be transmitted by blood transfusion has been documented in humans11-13. The finding of DENV-NS1 antigen in 1% of the blood donors tested in this study suggests that these donors were actively infected with the DENV and had ongoing asymptomatic viraemia or were sub-clinical carriers of the virus 11-13. It is conceivable that blood from NS1-positive, active carriers of DENV could transmit the infection to recipients14,15. Indeed, DENV RNA has been detected in asymptomatic blood donors whose sera were either positive for IgM or lacked detectable levels of specific antibody to DENV; this phenomenon is found worldwide in areas in which Dengue is endemic and the incidence varies depending on the season and year10,16-18. Importantly, recipients of blood from asymptomatic DENV-infected donors have been reported to develop fever associated with neutropenia, severe thrombocytopenia and hypotension 3 days after the blood transfusion19-21. Given that blood donations are still not routinely screened for DENV, asymptomatic DENV-infected donors may silently transmit the virus to prospective recipients, and so stake holders in blood transfusion practices should consider DENV as a potential threat to transfusion safety14,15. From the point of view of feasibility and cost-effectiveness of screening for DENV, it should be noted that the majority of the previous studies in blood donors were based on the expensive detection of viral ribonucleic acid, which may not be affordable as a routine screening tool for average blood banks in countries with limited financial resources. ELISA screening for DENV-NS1 antigen is, however, feasible and less expensive. Impact of transmission of anti-DENV antibodies via transfusion Recently, it has been proposed that not only DENV itself but also its antibodies may pose a risk to blood transfusion safety 11. The presence of anti-DENV antibodies in donated blood has been demonstrated in a number of studies worldwide11,14,22. In this study IgM and IgG anti-DENV antibodies were detected in the serum of 6% and 7%, respectively, of the tested blood donors. Detection of anti-DENV IgM/IgG antibodies may indicate the presence of primary and/or secondary DENV infections depending on the antibody titres, and positivity for IgM points to an ongoing infection suggesting that the donor is in a carrier stage of infection15. Clinically, it is well known that the serious forms of Dengue disease (Dengue haemorrhagic fever and/or Dengue shock syndrome) are more likely to occur during a second infection with a different DENV serotype from that which caused the primary infection11,23. The precise pathophysiology of this effect is unclear; however, Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14
136
Dengue virus infection among Saudi blood donors
the most accepted pathogenic hypotheses are related to the role of heterotypic non-neutralising or partially neutralising anti-DENV antibodies in a phenomenon known as antibody-dependent enhancement (ADE)23. In ADE, both circulating neutralising and non-neutralising (or partially neutralising) antiviral antibodies are present in a person who has been infected by one DENV serotype. If a second infection by a different DENV serotype occurs, the virus may be recognised by these cross-reactive heterotypic non-neutralising and subneutralising antibodies, resulting in antigen-antibody complex formation. These complexes enhance viral penetration and replication in Fcγ receptor-bearing cells such as monocytes/macrophages, a major site of DENV replication in vivo, leading to the release of vasoactive mediators, increased vascular permeability, plasma leakage and, possibly, to the development of hypovolaemic shock and life-threatening forms of the disease23,24. In addition, it has been hypothesised that binding of the second DENV serotype to the heterotypic non-neutralising antibodies may deliver the virus into the wrong compartment of dendritic cells that have ingested it for destruction. Once inside the white blood cell, the virus replicates undetected, eventually generating very high titres of virus, thereby causing severe disease24. Furthermore, Modhiran et al.25 suggested that DENV-ADE has a negative impact on toll-like receptordependent signalling pathways with suppression of innate immune responses that occur specifically during the severe form of DENV infection but not in the mild form of the disease. Although the DENV-ADE appears to be involved in the development of more serious disease, prospective studies are needed to determine the possible importance of this phenomenon in transfused subjects who receive non-neutralising anti-DENV antibodies from DENV-infected donors and are later exposed to heterotypic DENV infection.
Conclusions
This study provides the first data on seropositivity for DENV and its antibodies among Saudi Arabian blood donors and highlights the importance of establishing quantitative or molecular serological methods for screening for DENV and/or its antibodies in blood donors in this country, so that the quality of blood transfusions is guaranteed and the endemicity of DENV is reduced. However, a few limitations of the study must be mentioned. First, the participants were all males and the study population comprised only 100 subjects. This lack of representativeness of the general population could have led to the inferred prevalence being either underestimated or overestimated. Second, we did not confirm the active viral infection in DENV-NS1-positive samples by polymerase chain reaction analysis. Thus, further studies
should be performed to confirm the findings of the present study and its related recommendation.
Acknowledgements
This work was financially supported by a grant (43409045) from the Institute of Scientific Research (ISRRIH), Umm Al-Qura University, Kingdom of Saudi Arabia. Keywords: Dengue virus, Saudi Arabia, blood donors, seroprevalence. The Author declares no conflicts of interest.
References
1) Arima Y, Edelstein ZR, Han HK, Matsui T. Epidemiologic update on the dengue situation in the Western Pacific Region. Western Pac Surveill Response J 2013; 4: 47-54. 2) Normile D. Surprising new dengue virus throws a spanner in disease control efforts. Science 2013; 342: 415. 3) Fakeeh M, Zaki A. Virologic and serologic surveillance for dengue fever in Jeddah, Saudi Arabia, 1994-1999. Am J Trop Med Hyg 2001; 65: 764-7. 4) Khan NA, Azhar EI, El-Fiky S, et al. Clinical profile and outcome of hospitalized patients during first outbreak of dengue in Makkah, Saudi Arabia. Acta Trop 2008; 105: 39-44. 5) Azhar E, Kao M, Niedrig M, Masri B, et al. Virological diagnosis of dengue fever in Jeddah, Saudi Arabia: comparison between RT-PCR and virus isolation in cell culture. Infect Dis Immun 2010; 2: 24-9. 6) Aziz AT, Dieng H, Ahmad AH, et al. Household survey of container-breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia. Asian Pac J Trop Biomed 2012; 2: 849-57. 7) Wilder-Smith A, Chen LH, Massad E, Wilson ME. Threat of dengue to blood safety in dengue-endemic countries. Emerg Infect Dis 2009; 15: 8-11. 8) Pozzetto B, Garraud O. Emergent viral threats in blood transfusion. Transfus Clin Biol 2011; 18: 174-83. 9) Tomashek KM, Margolis HS. Dengue: a potential transfusiontransmitted disease. Transfusion 2011; 51: 1654-60. 10) Lanteri MC, Busch MP. Dengue in the context of "safe blood" and global epidemiology: to screen or not to screen? Transfusion 2012; 52: 1634-9. 11) Ribas-Silva RC, Eid AA. Dengue antibodies in blood donors. Rev Bras Hematol Hemoter 2012; 34: 193-5. 12) Stramer SL, Linnen JM, Carrick JM, et al. Dengue viremia in blood donors identified by RNA and detection of dengue transfusion transmission during the 2007 dengue outbreak in Puerto Rico. Transfusion 2012; 52: 1657-66. 13) Beatty ME, Biggerstaff B, Rigau J, Petersen L. Estimated risk of transmission of dengue virus through blood transfusion in Puerto Rico (Abstract #126):Proceedings of the 5 th International Conference on Emerging Infectious Diseases; Atlanta, Georgia, USA; March 19-22, 2006. 14) Faddy HM, Seed CR, Fryk JJ, et al. Implications of dengue outbreaks for blood supply, Australia. Emerg Infect Dis 2013; 19: 787-9. 15) Harif NF, Kader ZSA, Joshi SR, Yusoff NM. Seropositive status of dengue virus infection among blood donors in North Malaysia. Asian J Transfus Sci 2014; 8: 64. 16) Linnen JM, Vinelli E, Sabino EC, et al. Dengue viremia in blood donors from Honduras, Brazil, and Australia. Transfusion 2008; 48: 1355-62.
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 137
Ashshi AM 17) Petersen LR, Tomashek KM, Biggerstaff BJ. Estimated prevalence of dengue viremia in Puerto Rican blood donations, 1995 through 2010. Transfusion 2012; 52: 1647-51. 18) Dias LL, Amarilla AA, Poloni TR, et al. Detection of dengue virus in sera of Brazilian blood donors. Transfusion 2012; 52: 1667-71. 19) Chuang V, Wong TY, Leung YH, et al. Transfer of dengue through blood transfusion. Hong Kong Med J 2008; 14: 170-7. 20) Tambyah PA, Koay ES, Poon ML, et al. Dengue hemorrhagic fever transmitted by blood transfusion. N Engl J Med 2008; 359: 1526-7. 21) Chastel C. Eventual role of asymptomatic cases of dengue for the introduction and spread of dengue viruses in non-endemic regions. Front Physiol 2012; 20: 70. 22) Vairo F, Nicastri E, Yussuf SM, et al. IgG against dengue virus in healthy blood donors, Zanzibar, Tanzania. Emerg Infect Dis 2014; 20: 465-8. 23) Murphy BR, Whitehead SS. Immune response to dengue virus and prospects for a vaccine. Annu Rev Immunol 2011; 29: 587-619.
24) Dejnirattisai W, Jumnainsong A, Onsirisakul N, et al. Crossreacting antibodies enhance dengue virus infection in humans. Science 2010; 328: 745-8. 25) Modhiran N, Kalayanarooj S, Ubol S. Subversion of innate defenses by the interplay between DENV and pre-existing enhancing antibodies: TLRs signaling collapse. PLoS Negl Trop Dis 2010; 4: e924.
Arrived: 31 May 2014 - Revision accepted: 13 October 2014 Correspondence: Ahmed Mohammed Ashshi Department of Laboratory Medicine Faculty of Applied Medical Sciences Umm Al-Qura University Holy Makkah, PO Box 7607 Kingdom of Saudi Arabia e-mail: [email protected]
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 138
Introduction
Dengue is the most important mosquito-borne viral disease in the world and is endemic in more than 100 countries, with an estimated 100 million infected cases and 25,000 deaths per year worldwide1. Dengue virus (DENV) is caused by a single-stranded RNA virus with five serotypes (DENV-1, DENV-2, DENV-3, DENV-4 and DENV-5)1,2 and its clinical picture ranges from relatively mild Dengue fever, to the life-threatening Dengue haemorrhagic fever/Dengue shock syndrome. In Saudi Arabia, an outbreak of Dengue was reported for the first time in Jeddah during the 1990s3. Next, two peaks of infections were reported during 20052006 and another two peaks in 2008. After that, both Dengue disease and its serious haemorrhagic forms became endemic in the Western and Southern regions of the Kingdom4-6. So far, Aedes aegypti remains the mosquito vector most strongly implicated in Dengue transmission and endemicity in this country, although Aedes albopictus is also incriminated6. The potential role of foreign visitors, including pilgrims, who arrive from neighbouring African and Southeast Asia countries with known Dengue endemicity, is also a concern. Millions of visitors come annually from the whole world to the Holy Mecca. Some of these visitors may arrive during their viraemic stage of Dengue infection and, thereby, facilitate the spread of DENV4-6. Emerging infectious diseases still pose threats and risks to the safety of blood products and transfusions. Special attention has recently been paid to the significant role of blood transfusion in the transmission of DENV from asymptomatic infected blood donors to recipients. This form of viral transmission is another source of dissemination and endemicity of the virus in the community7-10. The presence of anti-DENV antibodies is a further important cause of concern in transfusion medicine. It has been proposed that transfusion of blood from donors with circulating non-neutralising or partially neutralising anti-DENV antibodies may increase the susceptibility of recipients to immunological conditions, with these recipients being at a higher risk of haemorrhagic Dengue if they are exposed to a later infection by another DENV serotype within 6 months after the transfusion11. Furthermore, the transmission of
heterotypic anti-DENV antibodies from infected blood donors may enhance viral infectivity in recipients who are later exposed to another DENV serotype11. Given the absence of an approved blood screening test for DENV in Saudi Arabia and in response to the new epidemiological situation, the current pilot study was designed to determine the seroprevalence of DENV infection and/or its antibodies among blood donors in the Holy Mecca in order to improve the safety of the blood supply and products in blood donation services in Saudi Arabia.
Materials and methods
Ethical approval Ethical approval was obtained from Umm Al-Qura Institutional Review Ethics Committee before starting the study and all blood samples were collected after informed, written consent had been given by the participants. Participants, blood sampling and screening This cross-sectional seroprevalence study was conducted at the blood transfusion service in Heraa' General Hospital, Holy Mecca, Saudi Arabia. From January to April 2014, a total of 100 healthy eligible Saudi male blood donors (aged between 25 and 50 years old), who were negative for infections with human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) and who were accepted for blood donation according to the policy set up by the Kingdom of Saudi Arabia Health Ministry, were randomly included. From each enrolled donor, 10 mL of whole venous blood was collected into tubes without anticoagulant. The tubes were centrifuged at 3,000 rpm for 15 minutes to obtain serum. Sera were then stored in a freezer at −20 °C until screened. At the end of the collection phase, the samples of serum were screened for DENV non-structural protein 1 (NS1) antigen, anti-DENV IgM and IgG antibodies using a commercially available Dengue virus Pan-E NS1 early enzyme-linked immunosorbent assay (ELISA), Dengue virus IgM capture ELISA, and Dengue virus IgG capture ELISA, respectively (all from Panbio, Brisbane, Australia). In each assay, all samples were processed in duplicate,
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 © SIMTI Servizi Srl
135
Ashshi AM
according to the manufacturer's instructions, and were repeated again if the results from the duplicate testing were not concordant. Data interpretation According to the manufacturer's recommendations, a positive ELISA result for either DENV-NS1 antigen or anti-DENV IgM antibody was defined as an index value >11 Panbio Units (PU), while a positive ELISA result for anti-DENV IgG antibody was defined as an index value >22 PU. Index values of 9-11 PU for either DENV-NS1 antigen or anti-DENV IgM antibody and index values of 18-22 PU for anti-DENV IgG antibody were considered as equivocal reactions, in accordance with the manufacturer's recommendations.
Results
Transfusion safety is of paramount importance to the recipient of blood products. In recent decades, the safety of blood products with regards to the risk of HIV, HBV and HCV infections has increased dramatically; however, emerging infectious diseases pose new threats to the recipients of blood transfusions8. The risks of transfusion-associated transmission of DENV and/or its antibodies are emerging worldwide9-13. Dengue is an endemic disease in Saudi Arabia, particularly in its Western region3-6, yet there is no approved blood screening test for DENV infection in this country. This aim of this study was to determine, for the first time, the seroprevalance of DENV infection and its antibodies among Saudi blood donors who live in the Holy Mecca. In the present preliminary study, 100 healthy adult male Saudi blood donors, negative for HIV, HCV and HBV infections and accepted for blood donation according to the policy set up by the Kingdom of Saudi Arabia Health Ministry, were screened for DENVNS1 antigen and IgM and IgG anti-DENV antibodies using commercially available ELISA kits (Panbio). As shown in Table I, among the tested donors, 1% showed positivity for DENV-NS1 antigen, 6% were positive for anti-DENV IgM antibody and 7% were positive for anti-DENV IgG antibody. There were also equivocal results for NS1 antigen (1%), IgM antibody (1%), and IgG antibody (1%) (data not shown). Table I - Results of screening for DENV infection among 100 blood donors. Tested blood donors 100
DENV-NS1 positivity* 1 (1%)
Anti-DENV antibody positivity* IgM only
IgG only
IgM + IgG
6 (6%)
7 (7%)
0 (0%)
DENV: Dengue virus; NS1: non-structural protein 1 antigen; IgM: immunoglobulin M antibody; IgG: immunoglobulin G antibody. * Values of DENV-NS1 antigen or anti-DENV IgM antibodies are considered positive when >11 Panbio Units, while values of anti-DENV IgG antibodies considered positive are >22 Panbio Units.
Discussion
The fact that DENV can be transmitted by blood transfusion has been documented in humans11-13. The finding of DENV-NS1 antigen in 1% of the blood donors tested in this study suggests that these donors were actively infected with the DENV and had ongoing asymptomatic viraemia or were sub-clinical carriers of the virus 11-13. It is conceivable that blood from NS1-positive, active carriers of DENV could transmit the infection to recipients14,15. Indeed, DENV RNA has been detected in asymptomatic blood donors whose sera were either positive for IgM or lacked detectable levels of specific antibody to DENV; this phenomenon is found worldwide in areas in which Dengue is endemic and the incidence varies depending on the season and year10,16-18. Importantly, recipients of blood from asymptomatic DENV-infected donors have been reported to develop fever associated with neutropenia, severe thrombocytopenia and hypotension 3 days after the blood transfusion19-21. Given that blood donations are still not routinely screened for DENV, asymptomatic DENV-infected donors may silently transmit the virus to prospective recipients, and so stake holders in blood transfusion practices should consider DENV as a potential threat to transfusion safety14,15. From the point of view of feasibility and cost-effectiveness of screening for DENV, it should be noted that the majority of the previous studies in blood donors were based on the expensive detection of viral ribonucleic acid, which may not be affordable as a routine screening tool for average blood banks in countries with limited financial resources. ELISA screening for DENV-NS1 antigen is, however, feasible and less expensive. Impact of transmission of anti-DENV antibodies via transfusion Recently, it has been proposed that not only DENV itself but also its antibodies may pose a risk to blood transfusion safety 11. The presence of anti-DENV antibodies in donated blood has been demonstrated in a number of studies worldwide11,14,22. In this study IgM and IgG anti-DENV antibodies were detected in the serum of 6% and 7%, respectively, of the tested blood donors. Detection of anti-DENV IgM/IgG antibodies may indicate the presence of primary and/or secondary DENV infections depending on the antibody titres, and positivity for IgM points to an ongoing infection suggesting that the donor is in a carrier stage of infection15. Clinically, it is well known that the serious forms of Dengue disease (Dengue haemorrhagic fever and/or Dengue shock syndrome) are more likely to occur during a second infection with a different DENV serotype from that which caused the primary infection11,23. The precise pathophysiology of this effect is unclear; however, Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14
136
Dengue virus infection among Saudi blood donors
the most accepted pathogenic hypotheses are related to the role of heterotypic non-neutralising or partially neutralising anti-DENV antibodies in a phenomenon known as antibody-dependent enhancement (ADE)23. In ADE, both circulating neutralising and non-neutralising (or partially neutralising) antiviral antibodies are present in a person who has been infected by one DENV serotype. If a second infection by a different DENV serotype occurs, the virus may be recognised by these cross-reactive heterotypic non-neutralising and subneutralising antibodies, resulting in antigen-antibody complex formation. These complexes enhance viral penetration and replication in Fcγ receptor-bearing cells such as monocytes/macrophages, a major site of DENV replication in vivo, leading to the release of vasoactive mediators, increased vascular permeability, plasma leakage and, possibly, to the development of hypovolaemic shock and life-threatening forms of the disease23,24. In addition, it has been hypothesised that binding of the second DENV serotype to the heterotypic non-neutralising antibodies may deliver the virus into the wrong compartment of dendritic cells that have ingested it for destruction. Once inside the white blood cell, the virus replicates undetected, eventually generating very high titres of virus, thereby causing severe disease24. Furthermore, Modhiran et al.25 suggested that DENV-ADE has a negative impact on toll-like receptordependent signalling pathways with suppression of innate immune responses that occur specifically during the severe form of DENV infection but not in the mild form of the disease. Although the DENV-ADE appears to be involved in the development of more serious disease, prospective studies are needed to determine the possible importance of this phenomenon in transfused subjects who receive non-neutralising anti-DENV antibodies from DENV-infected donors and are later exposed to heterotypic DENV infection.
Conclusions
This study provides the first data on seropositivity for DENV and its antibodies among Saudi Arabian blood donors and highlights the importance of establishing quantitative or molecular serological methods for screening for DENV and/or its antibodies in blood donors in this country, so that the quality of blood transfusions is guaranteed and the endemicity of DENV is reduced. However, a few limitations of the study must be mentioned. First, the participants were all males and the study population comprised only 100 subjects. This lack of representativeness of the general population could have led to the inferred prevalence being either underestimated or overestimated. Second, we did not confirm the active viral infection in DENV-NS1-positive samples by polymerase chain reaction analysis. Thus, further studies
should be performed to confirm the findings of the present study and its related recommendation.
Acknowledgements
This work was financially supported by a grant (43409045) from the Institute of Scientific Research (ISRRIH), Umm Al-Qura University, Kingdom of Saudi Arabia. Keywords: Dengue virus, Saudi Arabia, blood donors, seroprevalence. The Author declares no conflicts of interest.
References
1) Arima Y, Edelstein ZR, Han HK, Matsui T. Epidemiologic update on the dengue situation in the Western Pacific Region. Western Pac Surveill Response J 2013; 4: 47-54. 2) Normile D. Surprising new dengue virus throws a spanner in disease control efforts. Science 2013; 342: 415. 3) Fakeeh M, Zaki A. Virologic and serologic surveillance for dengue fever in Jeddah, Saudi Arabia, 1994-1999. Am J Trop Med Hyg 2001; 65: 764-7. 4) Khan NA, Azhar EI, El-Fiky S, et al. Clinical profile and outcome of hospitalized patients during first outbreak of dengue in Makkah, Saudi Arabia. Acta Trop 2008; 105: 39-44. 5) Azhar E, Kao M, Niedrig M, Masri B, et al. Virological diagnosis of dengue fever in Jeddah, Saudi Arabia: comparison between RT-PCR and virus isolation in cell culture. Infect Dis Immun 2010; 2: 24-9. 6) Aziz AT, Dieng H, Ahmad AH, et al. Household survey of container-breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia. Asian Pac J Trop Biomed 2012; 2: 849-57. 7) Wilder-Smith A, Chen LH, Massad E, Wilson ME. Threat of dengue to blood safety in dengue-endemic countries. Emerg Infect Dis 2009; 15: 8-11. 8) Pozzetto B, Garraud O. Emergent viral threats in blood transfusion. Transfus Clin Biol 2011; 18: 174-83. 9) Tomashek KM, Margolis HS. Dengue: a potential transfusiontransmitted disease. Transfusion 2011; 51: 1654-60. 10) Lanteri MC, Busch MP. Dengue in the context of "safe blood" and global epidemiology: to screen or not to screen? Transfusion 2012; 52: 1634-9. 11) Ribas-Silva RC, Eid AA. Dengue antibodies in blood donors. Rev Bras Hematol Hemoter 2012; 34: 193-5. 12) Stramer SL, Linnen JM, Carrick JM, et al. Dengue viremia in blood donors identified by RNA and detection of dengue transfusion transmission during the 2007 dengue outbreak in Puerto Rico. Transfusion 2012; 52: 1657-66. 13) Beatty ME, Biggerstaff B, Rigau J, Petersen L. Estimated risk of transmission of dengue virus through blood transfusion in Puerto Rico (Abstract #126):Proceedings of the 5 th International Conference on Emerging Infectious Diseases; Atlanta, Georgia, USA; March 19-22, 2006. 14) Faddy HM, Seed CR, Fryk JJ, et al. Implications of dengue outbreaks for blood supply, Australia. Emerg Infect Dis 2013; 19: 787-9. 15) Harif NF, Kader ZSA, Joshi SR, Yusoff NM. Seropositive status of dengue virus infection among blood donors in North Malaysia. Asian J Transfus Sci 2014; 8: 64. 16) Linnen JM, Vinelli E, Sabino EC, et al. Dengue viremia in blood donors from Honduras, Brazil, and Australia. Transfusion 2008; 48: 1355-62.
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 137
Ashshi AM 17) Petersen LR, Tomashek KM, Biggerstaff BJ. Estimated prevalence of dengue viremia in Puerto Rican blood donations, 1995 through 2010. Transfusion 2012; 52: 1647-51. 18) Dias LL, Amarilla AA, Poloni TR, et al. Detection of dengue virus in sera of Brazilian blood donors. Transfusion 2012; 52: 1667-71. 19) Chuang V, Wong TY, Leung YH, et al. Transfer of dengue through blood transfusion. Hong Kong Med J 2008; 14: 170-7. 20) Tambyah PA, Koay ES, Poon ML, et al. Dengue hemorrhagic fever transmitted by blood transfusion. N Engl J Med 2008; 359: 1526-7. 21) Chastel C. Eventual role of asymptomatic cases of dengue for the introduction and spread of dengue viruses in non-endemic regions. Front Physiol 2012; 20: 70. 22) Vairo F, Nicastri E, Yussuf SM, et al. IgG against dengue virus in healthy blood donors, Zanzibar, Tanzania. Emerg Infect Dis 2014; 20: 465-8. 23) Murphy BR, Whitehead SS. Immune response to dengue virus and prospects for a vaccine. Annu Rev Immunol 2011; 29: 587-619.
24) Dejnirattisai W, Jumnainsong A, Onsirisakul N, et al. Crossreacting antibodies enhance dengue virus infection in humans. Science 2010; 328: 745-8. 25) Modhiran N, Kalayanarooj S, Ubol S. Subversion of innate defenses by the interplay between DENV and pre-existing enhancing antibodies: TLRs signaling collapse. PLoS Negl Trop Dis 2010; 4: e924.
Arrived: 31 May 2014 - Revision accepted: 13 October 2014 Correspondence: Ahmed Mohammed Ashshi Department of Laboratory Medicine Faculty of Applied Medical Sciences Umm Al-Qura University Holy Makkah, PO Box 7607 Kingdom of Saudi Arabia e-mail: [email protected]
Blood Transfus 2015; 13: 135-8 DOI 10.2450/2014.0134-14 138
