M.P. Busch

Impact of specimen handling and storage on detection of hepatitis C virus RNA

Direct detection of hepatitis C virus (HCV) RNA in serum or plasma is useful for validating the performance of anti‐HCV assays and for the discrimination of persons with persistent HCV infections from those with resolved infections. Quantitation of HCV RNA may also be useful for disease prognosis and therapeutic monitoring. Previous studies have reported detection of HCV RNA in 50 to 70 percent of blood donors who were positive on anti‐HCV supplemental tests. There is concern that specimen processing and storage conditions might influence the stability, and hence the detectability, of HCV RNA. To address this concern, the rate of detection of HCV RNA by the polymerase chain reaction (PCR) using donor pilot tube sera (PTS) previously subjected to routine donor screening and supplemental testing was compared with HCV PCR results obtained with fresh‐frozen plasma (FFP) derived from the same donations. All 16 anti‐HCV supplemental test‐positive donations evaluated were HCV RNA positive with FFP, whereas only 10 (62.5%) were positive with PTS (p = 0.024). None of 11 FFP or PTS samples from HCV enzyme immunoassay‐reactive donations not confirmed by supplemental anti‐HCV assays tested positive for HCV RNA. Direct comparison of sample type (serum vs. plasma) and various storage conditions using specimens from two seropositive donors showed that room‐temperature storage results in marked reduction in HCV RNA signal, while replicate freezing and thawing caused a moderate reduction. These data indicate that well‐controlled sample processing and storage conditions are critical to the sensitive and potentially quantitative analysis of HCV RNA.

Declining value of alanine aminotransferase in screening of blood donors to prevent posttransfusion hepatitis B and C virus infection. The Retrovirus Epidemiology Donor Study.

BACKGROUND: Since the mid‐1980s, blood banks in the United States have screened donors for elevated alanine aminotransferase (ALT) in an effort to prevent posttransfusion hepatitis. The present study was designed to quantitate the residual value of ALT screening following the implementation of hepatitis C virus (HCV) assays.

First report of human immunodeficiency virus transmission via an RNA‐screened blood donation

Background and Objectives  Blood banks in the USA have recently introduced minipool nucleic acid amplification testing (MP‐NAT) of blood products to reduce the transmission of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) by transfusions. However, MP‐NAT is limited in its ability to detect preseroconversion samples with very low viral RNA loads.

A method for estimating hepatitis B virus incidence rates in volunteer blood donors. National Heart, Lung, and Blood Institute Retrovirus Epidemiology Donor Study

BACKGROUND: Calculations of the incidence of hepatitis B virus (HBV) infections in the blood donor setting that are based solely on data for seroconversion to hepatitis B surface antigen (HBsAg) will underestimate the incidence due to the transient nature of antigenemia. Estimates based on antibody to hepatitis B core antigen will overestimate the incidence due to false‐positive results caused by the nonspecificity of the test. STUDY DESIGN AND METHODS: Serologic test results were obtained from multiple‐time volunteer donors at five United States blood centers from January 1991 through December 1993. The observed HBsAg seroconversion rate was multiplied by an adjustment factor, derived from the weighted average probability of a positive HBsAg test for HBV‐infected donors who become chronic carriers, for donors with a primary antibody response without detectable antigenemia, and for donors who develop transient antigenemia. RESULTS: Among 586,507 multiple‐time donors giving 2,318,356 donations and observed for 822,426 person‐years, the HBsAg incidence rate was 4.01 per 100,000 person‐years. On the basis of prior reports of the duration of HBsAg positivity and the observed distribution of interdonation intervals among the study group, there was an estimated 53‐percent chance that an HBV‐infected donor with transient antigenemia would have a positive HBsAg test result. If 70 percent of newly HBV‐infected adults have transient antigenemia, 25 percent have a primary antibody response without primary antigenemia, and 5 percent become chronic carriers, the overall chance of being detected by the HBsAg test was 42 percent, for an adjustment factor of 2.38. The total HBV incidence rate, therefore, was estimated to be 9.54 per 100,000 person‐years. CONCLUSION: The crude HBV incidence rate observed from HBsAg test results will underestimate the true rate. The adjusted HBV incidence rate should be used in applications such as estimations of residual HBV risk to the blood supply and projections of the benefits of screening for HBV DNA.

Transfusion‐transmitted arboviruses

There exists considerable risk for transfusion transmission of arboviruses due to short periods of asymptomatic viraemia in populations with variable and sometimes extremely high incidence of arboviral infections. Aside from West Nile virus, few arbovirus transfusion transmissions have been proven, mostly due to difficulties in ruling out vector‐borne transmission in recipients with arbovirus disease. Nevertheless, arbovirus transfusion risk models and assessments of viraemia prevalence in blood donations indicate substantial transfusion transmission of dengue and Chikungunya viruses in epidemic areas. Many other arboviruses, several of which are importation risks in the Americas, Europe and Asia, also cause large outbreaks and threaten transfusion safety. Prevention largely depends on excluding donors from outbreak areas or implementation of highly sensitive nucleic acid amplification tests. Because of the increasing emergence of arboviral disease globally, it is prudent to prepare for both endemic and exotic arboviruses capable of producing large epidemics and subsequent transfusion transmission risk.

Clearance of hepatitis C virus RNA from the peripheral blood mononuclear cells of blood donors who spontaneously or therapeutically control their plasma viremia.

We determined whether hepatitis C virus (HCV) RNA could be detected associated with peripheral blood mononuclear cells (PBMC) of seropositive blood donors who had spontaneously or therapeutically cleared their plasma viremia. Blood donor plasma viremia status was first determined with a highly sensitive transcription‐mediated amplification (TMA) test performed in duplicate assays. PBMC from 69 aviremic and 56 viremic blood donors were then analyzed for the presence of HCV RNA with TMA adapted to detect viral RNA in PBMC and with a reverse transcription–nested polymerase chain reaction assay. PBMC‐associated HCV RNA was detected in none of the 69 aviremic donors, including all 6 subjects with a sustained viral response following antiviral therapy. PBMC‐associated HCV RNA was detected in 43 of the 56 viremic donors. The 13 viremic donors with no detectable PBMC‐associated HCV RNA all had very low viral loads (6 positive only in 1 of 2 duplicate plasma TMA assays, 6 with viral loads below 100 HCV RNA copies/mL, and 1 with a viremia of 2700 HCV RNA copies/mL). The absence of detectable PBMC HCV RNA detection in all 69 aviremic donors reported here contrasts with prior studies, possibly as a result of the higher sensitivity of the TMA assay used to test for plasma viremia. Conclusion: Our results indicate that PBMC are unlikely to serve as a long‐lived reservoir of HCV in aviremic subjects. (HEPATOLOGY 2008.)

Transfusion transmission of highly prevalent commensal human viruses

BACKGROUND: Anellovirus species Torque teno virus (TTV), Torque teno mini virus (TTMV), and Torque teno midi virus (TTMDV) and flavivirus GBV‐C are highly prevalent and genetically diverse chronic human viral infections that have not yet been associated with disease.

Demographic characteristics and prevalence of serologic markers among donors who use the confidential unit exclusion process : the Retrovirus Epidemiology Donor Study

BACKGROUND: Most blood centers utilize a confidential unit exclusion (CUE) process, intended to reduce the risk of transfusion‐associated infectious diseases by allowing high‐risk donors confidentially to exclude their blood from use for transfusion. The effectiveness of this method remains controversial. STUDY DESIGN AND METHODS: Confirmatory or supplemental test results for antibodies to human immunodeficiency virus, human T‐lymphotropic virus type I, and hepatitis C virus, as well as hepatitis B surface antigen and syphilis and screening test results for antibodies to hepatitis B core (antigen) and alanine aminotransferase levels were obtained for approximately 1.8 million units donated during 1991 and 1992 at five blood centers within the United States. The prevalences of these infectious disease markers in units that the donors confidentially excluded (CUE+) and units that the donors did not exclude (CUE‐) were calculated and examined within demographic subgroups. RESULTS: Units that were CUE+ were 8 to 41 times more likely to be seropositive for antibodies to human immunodeficiency virus and hepatitis C virus, hepatitis B surface antigen, and syphilis and three to four times more likely to react for antibody to hepatitis B core (antigen) or to have elevated alanine aminotransferase levels than units that were CUE‐ (p < 0.001). The positive predictive value of CUE (the percentage of CUE+ units that were confirmed seropositive for any marker) was 3.5 percent, and the sensitivity of CUE (the percentage of confirmed‐seropositive units that were CUE+) was 2.3 percent. CONCLUSION: The current CUE process has low sensitivity and apparently low positive predictive value, and in many cases, it appeared that donors misunderstood it. Yet, CUE was not a “random process,” as CUE+ units were more likely to be seropositive for any infectious disease marker than CUE‐ units. This suggests that efforts to improve the CUE system may be warranted. As risk factors for transfusion‐transmitted infection become more difficult to identify by history‐based screening, however, such efforts may have limited effect.

Demographic characteristics, unreported risk behaviors, and the prevalence and incidence of viral infections: a comparison of apheresis and whole‐blood donors. The Retrovirus Epidemiology Donor Study

BACKGROUND: The demographics, deferrable risk behaviors, and the prevalence and incidence of viral infections of apheresis (PH) and whole‐blood (WB) donors were compared, to characterize these two populations and to evaluate the relative safety of PH and WB donors in terms of transfusion‐transmitted viral infections.

Human immunodeficiency virus‐1 and hepatitis C virus RNA among South African blood donors: estimation of residual transfusion risk and yield of nucleic acid testing

Background and Objectives South Africa is an endemic area for human immunodeficiency virus 1 (HIV‐1) infection, which has an impact on the safety of the blood supply. We studied the presence of HIV‐1 and hepatitis C virus (HCV) RNA, and recent HIV seroconversion, in blood donors in order to estimate transfusion risk and to determine whether nucleic acid testing (NAT) could effectively improve blood safety.