Two human immunodeficiency virus Type 2 cases in US blood donors including serologic, molecular, and genomic characterization of an epidemiologically unusual case.

BACKGROUND: Blood donation screening for human immunodeficiency virus Type 2 (HIV-2) has been in place in the United States since 1992. However, only three HIV-2 antibody-positive donors have been reported to date, all detected via HIV-1 cross-reactivity.

STUDY DESIGN AND METHODS: Here we identify two additional HIV-2-positive donors by routine anti-HIV-1 and anti-HIV-2 screening, including a first-time male donor living in Georgia having recently immigrated to the United States from West Africa (from a 1998 donation) and a Taiwanese female repeat donor (nurse) living in California with no travel outside of Taiwan or apparent connections to West Africa (from a 2015 donation). Neither donor acknowledged any risk factors, and both remained asymptomatic through follow-up. The second donor was further investigated by serologic, molecular, and genomic assays because of her unusual demographics. She was documented to harbor HIV-2 RNA, albeit sporadically by HIV-2-specific nucleic acid tests (35%-100% of replicates) and at very low levels (<9.6 IU/mL). Metagenomic next-generation sequencing (mNGS) confirmed the identification of a Group B HIV-2 strain, with recovered reads covering 46.9% of the predicted genome.

CONCLUSIONS: The estimated frequency of an HIV-2-positive blood donor in the United States is one in 57 million donations. Due to the low frequency and low pathogenicity of HIV-2, public health and blood donation screening efforts must focus on HIV-1 detection and prevention. However, detection of HIV-2 infection in a donor with no apparent link to West Africa suggests that the United States must remain vigilant for HIV-2 virus infections. Ultradeep mNGS may be useful in the future for comprehensive identification of rare transfusion-transmissible agents.