Chronic Human Pegivirus 2 Without Hepatitis C Virus Co-Infection Kelly E

Chronic Human Pegivirus 2 without Hepatitis C Virus Co-infection Kelly E. Coller, Veronica Bruce, Michael Cassidy, Jeffrey Gersch, Matthew B. Frankel, Ana Vallari, Gavin Cloherty, John Hackett, Jr., Jennifer L. Evans, Kimberly Page, George J. Dawson Most human pegivirus 2 (HPgV-2) infections are associ- with risk for parenteral exposure), their HCV anti- ated with past or current hepatitis C virus (HCV) infection. body status was not determined (6,7). HPgV-2 is thought to be a bloodborne virus: higher prev- Previous studies indicate that HPgV-2 can estab- alence of active infection has been found in populations lish a chronic infection characterized by detectable with a history of parenteral exposure to viruses. We eval- viremia for >6 months (2,6). Most chronic HPgV-2 uated longitudinally collected blood samples obtained cases are associated with active HCV infection (2,6). from injection drug users (IDUs) for active and resolved In chronic HPgV-2 cases in which HCV RNA has not HPgV-2 infections using a combination of HPgV-2– been detected, the presence of HCV antibodies (indi- specific molecular and serologic tests. We found evi- cating a resolved infection) was not determined; thus, dence of HPgV-2 infection in 11.2% (22/197) of past or it is unclear whether previous HCV infection played current HCV-infected IDUs, compared with 1.9% (4/205) a role in the initial HPgV-2 infection. Despite observa- of an HCV-negative IDU population. Testing of available longitudinal blood samples from HPgV-2–positive partici- tions of HCV and HPgV-2 co-infection, no evidence pants identified 5 with chronic infection (>6 months vire- has been reported that HPgV-2 infection exacerbates mia in >3 timepoints); 2 were identified among the HCV- HCV infection (5,6,8) or that co-infection influences positive IDUs and 3 among the HCV-negative IDUs. Our the replication of either virus. findings indicate that HPgV-2 can establish chronic infec- We examined a cohort of IDUs for whom longi- tion and replicate in the absence of HCV. tudinal samples were available. We monitored the cohort for HCV status by HCV antibodies, RNA, or he recently identified second human pegivirus both, with the intent of capturing nascent HCV in- T(HPgV-2 or HHpgV-1) is a bloodborne flavivirus: fections (9). We performed initial testing for HPgV-2 little is known about the potential clinical significance (RNA and antibodies) on baseline and last collected of infection (1,2). Active or resolved HPgV-2 infec- samples. We further characterized longitudinal sam- tion has been detected worldwide in cohorts associ- ples from available participants that showed active or ated with risk for parenteral exposure to bloodborne resolved HPgV-2 infection upon testing initial or last pathogens (1,3–5). In a study in which hepatitis C vi- timepoints. We hypothesized that the IDUs would rus (HCV) status was determined (3), 1.2% of HCV have similar prevalence of HPgV-2 as shown in a pre- positive were actively infected with HPgV-2; none of vious study of HCV-infected persons with unknown the 1,306 HCV-negative participants (volunteer blood IDU status, and that by studying IDUs without HCV donors, HBV infected, HIV infected) were actively in- infection we would uncover HPgV-2 infection in the fected. In another study, participants with concurrent absence of HCV. Last, we hypothesized that longi- HIV/HCV infection or injection drug users (IDUs) had tudinal samples from IDUs would reveal whether a higher prevalence (3.0%–5.7%) of active HPgV-2 in- HPgV-2 can establish a persistent infection in the ab- fection (4–6). Although active HPgV-2 has been found sence of HCV co-infection. in other populations (e.g., hemophiliacs or others, Materials and Methods Author affiliations: Abbott Laboratories, Abbott Park, Illinois, USA (K.E. Coller, M. Cassidy, J. Gersch, M.B. Frankel, A. Vallari, Samples G. Cloherty, J. Hackett, Jr., G.J. Dawson); University of New We obtained samples from the U-Find-Out (UFO) Mexico, Albuquerque, New Mexico, USA (V. Bruce, K. Page); Study, an ongoing prospective observational study of University of California San Francisco, San Francisco, California, young adult active injectors, <30 years of age at en- USA (J.L. Evans) rollment, that was initiated in 2003 in the San Francis- DOI: https://doi.org/10.3201/eid2602.190434 co Bay area (California, USA). Details of enrollment Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 26, No. 2, February 2020 265 RESEARCH methods and follow-up have been described previ- or HCV antibodies), past or present; HCV-negative ously (9,10). In brief, young adult IDUs were recruit- is defined as no evidence (RNA or HCV antibodies), ed from neighborhoods where IDUs were known to past or present. congregate and invited to participate in a field study for eligibility screening. Eligible persons were those HPgV-2 Prevalence Study Design who reported injection drug use in the prior 30 days, We used previously described HPgV-2 molecular (11) were <30 years of age, spoke English, had no plans and serologic (3) assays to test all samples for deter- to travel outside of the San Francisco Bay area for >3 mining HPgV-2 prevalence. We divided them into months, and had negative or unknown HCV status. 3 testing groups: sample set 1, initial blood samples HCV antibody–positive persons were admitted into (n = 402); sample set 2, all last available follow-up the study if their HCV RNA status was negative or samples (n = 200); and sample set 3, any longitudi- unknown; those identified as HCV infected (RNA nal samples available for samples that were HPgV- positive) at baseline were not enrolled into follow-up. 2 (RNA or antibody) positive at initial or last draw Eligible consenting participants were asked to timepoint (n = 70) (Figure). Because the initial study complete a baseline interviewer-administered struc- collection targeted incident HCV infection, a limited tured questionnaire that queried sociodemographics, number of participants who were HCV positive at ini- parenteral and sexual risk behaviors and exposures, tial collection had follow-up samples available; only injecting exposures (e.g., frequency of injecting, num- 8 HCV-positive and 192 HCV-negative participants ber of persons injected with, types of drugs injected), from sample set 1 had follow-up (last) draw available alcohol use, and prevention and health service use. for testing, constituting sample set 2. They were also asked to provide blood samples for HCV testing, including both HCV antibodies and HPgV-2 Molecular Assay HCV RNA, and for storage. Before 2012, all partici- We used a modified version of the HPgV-2 reverse pants provided samples for HCV antibodies (using transcription PCR (RT-PCR) to determine HPgV-2 vi- standard laboratory-based testing) and for a qualita- remia (11). The RT-PCR targets 2 conserved regions of tive HCV RNA status determination using a nucleic the HPgV-2 genome within the 5′ untranslated region acid amplification test (Procliex HIV-1/HCV assay; (UTR) and the nonstructural (NS) 2–3 coding region Gen-Probe Inc., https://www.novartis.com). Begin- (11). We modified the assay to replace detection of ning in May 2012, HCV antibody testing was pri- HPgV RNA with an internal control. The internal con- marily conducted using a rapid test (OraSure Tech- trol was derived from the hydroxypyruvate reductase nologies, https://www.orasure.com) by fingerstick gene from the pumpkin plant, Cucurbita pepo, and is capillary blood collection; however, venipuncture delivered in an Armored RNA (Ambion, Inc., https:// was still used to collect specimens for RNA testing www.thermofisher.com) particle that has been dilut- and sample storage. Baseline samples on 402 partici- ed in negative human plasma (nonreactive for HBsAg, pants were selected as the initial sample set (Figure). HIV RNA, HCV RNA, HBV DNA, HIV-1/-2 antibod- A total of 205 (51.0%) samples were negative and ies, and HCV antibodies). We introduced the internal 197 (49.0%) positive for HCV antibodies and HCV control into each specimen at the beginning of sample RNA at baseline. HCV-positive in this current study preparation as a control for extraction and ampli- is defined as any evidence of HCV infection (RNA fication. We extracted samples from plasma using Figure. Design of study of chronic human pegivirus-2 and hepatitis C virus co-infection in injection drug users in the San Francisco Bay area, California, USA. Samples were tested using HPgV-2 molecular and serologic assays in 3 sample sets. HCV, hepatitis C virus; HPgV-2, human pegivirus 2. 266 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 26, No. 2, February 2020 Human Pegivirus 2 without Hepatitis C Co-infection the Abbott m2000sp instrument (Abbott Molecular, Last Sample Testing https://www.molecular.abbott) (open mode proto- Follow-up specimens were available for some study col m2000-RNA-Plasma-LL-500–110-v71408, version participants (sample set 2), primarily those who were 1.0). We used eluted nucleic acids immediately for HCV negative, due to the prospective design of the subsequent PCR analysis or stored them in the deep study that did not require follow-up samples from well plate at –80°C. HCV-positive participants (Figure). However, the study also included persons with newly detected HPgV-2 Antibody Testing HCV infection whom we followed to examine natural We screened research use–only assays to detect IgG re- history and resolution of incident HCV infection (9). sponse to HPgV-2 proteins for HPgV-2 seroconversion A total of 200 participants from baseline collection had (3). In brief, we built 2 separate indirect IgG assays for a final follow-up sample available for evaluation in use on the ARCHITECT instrument (Abbott Laborato- the HPgV-2 RNA and antibody assays; this group in- ries).

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