Seroprevalence of HTLV-1/2 Among Voluntary Blood Donors in Vietnam Duong Pham, 1 Dung Nguyen, 1 Tri Anh Nguyen, 1,{ Chi Tran, 1 Lan Tran, 1 Sushil Devare, 2 Anh Tran, 3,{ and Sonu Bhatnagar 4 Abstract Infection with human T lymphotropic virus (HTLV), although asymptomatic in most cases, can lead to severe illnesses, such as adult T cell leukemia/lymphoma or myelopathy/tropical spastic paraparesis. HTLV can be transmitted by whole-blood (WB) transfusion. The prevalence of HTLV among blood donor populations has not been characterized in Vietnam, although the screening has been partially implemented on voluntary basis since 2016. To determine the seroprevalence of HTLV-1/2 among blood donors, a total of 14,819 healthy blood donors in northern, central, and southern Vietnam and 1,003 samples from hepatitis B surface antigen (HbsAg), anti-hepatitis C (anti-HCV), or HIV Ag/Ab reactive blood donors were screened for anti-HTLV-1/2 antibodies by a chemiluminescence immunoassay using the Abbott ARCHITECT rHTLV-I/II assay. The anti-HTLV-1/2 repeat reactive (RR) samples were further tested by immunoblot (IB) method using MP Biomedicals HTLV Blot 2.4 for confirmation and differentiation of HTLV-1/2 infection. Proviral HTLV subgenomic amplification of the gag and tax regions was performed on the available WB RR samples (N = 11) by polymerase chain reaction (PCR). Among 14,819 blood donors, 34 samples (0.23%) were RR for anti-HTLV-1/2 antibodies, but only 1 case was confirmed HTLV-2 positive (0.0067%) and 5 cases were classified as indeterminate (0.034%) by IB. The RR rate was 0.39% among HBsAg/anti-HCV/HIV reactive sample groups, but none of them was confirmed by IB. Subgenomic PCR failed to amplify proviral DNA from WB samples of 11 RR samples. HTLV-1/2 prevalence was found to be low among blood donors in the study. Continued vigilance remains essential to maintain a low transfusion-transmitted risk in Vietnam. Keywords: HTLV, seroprevalence, Vietnam Introduction H uman T lymphotropic virus type-1 and -2 (HTLV-1/ 2) were discovered in the early 1980s 1 as pathogens leading to severe infection in humans. Soon after their dis- covery, it was realized that blood transfusion was associated with high rates of transmission due to the infusion of infected lymphocytes. Most of the infected people live without any symptoms; however, in a portion of carriers, HTLV-1 causes adult T cell leukemia (ATL), HTLV-1-associated myelopa- thy (HAM)/tropical spastic paraparesis, and HTLV-1 uveitis/ HTLV-1-associated uveitis after a long period of latency. 2 Since HTLV infection is often asymptomatic, clinically recognized reports of patients infected via blood transfusion are rare. However, there are case reports of transfusion- transmitted HTLV-1 infection associated with the acceler- ated onset of HAM, a debilitating spinal cord condition, while the development of post-transfusion ATL is very rare. 3–5 Since the virus has a long asymptomatic phase and high rates of seroconversion after transfusion, the risk of transmission from asymptomatic blood donors should be considered and appropriately managed, particularly in high- prevalence areas. As per the World Health Organization recommendations, the decision to screen donations for HTLV-1 infection should be made based on local epidemi- ological evidence. 6 1 Hematology and Blood Transfusion Center, National Institute of Hematology and Blood Transfusion, Hanoi, Vietnam. 2 Infectious Disease Research, Abbott Laboratories, Abbott Park, Illinois. 3 Abbott Diagnostics, Ho Chi Minh City, Vietnam. 4 Scientific Affairs, Abbott Laboratories, Singapore, Singapore. { Current affiliation: Member of the National Assembly, Chair of the Advisory Council–Medlatec Holdings, Tay Ho District, Hanoi, Vietnam. { Current affiliation: American Red Cross, Dakota Region, Fargo, North Dakota. AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 35, Number 4, 2019 ª Mary Ann Liebert, Inc. DOI: 10.1089/aid.2018.0240 376 Downloaded by 3.90.26.90 from www.liebertpub.com at 07/01/22. For personal use only.