Natural Killer (NK) cells are a crucial component of the host innate immune system with anti-viral and anti-cancer properties. However, the role of NK cells in West Nile virus (WNV) infection is controversial, with reported effects ranging from active suppression of virus to no effect at all. It was previously shown that K562-mb15-41BBL (K562D2) cells, which express IL-15 and 4-1BBL on the K562 cell surface, were able to expand and activate human primary NK cells of normal peripheral blood mononuclear cells (PBMC). The expanded NK cells were tested for their ability to inhibit WNV infection in vitro.

Background Female hormones are known to play an important role in predisposition for many infectious diseases. Recent work suggests there are gender effects in HIV/AIDS progression. Here we ask whether the sex steroid hormone β-estradiol affects the replication of HIV-1 or the efficacy of a common anti-retroviral drug, Stavudine (D4T). Results Human PBL were infected with HIV-1 in the presence or absence of combinations of sex steroid hormones and the anti-retroviral drug, D4T. After seven days in culture, viral supernatants were assayed for HIV-1 p24 protein. β-estradiol resulted in a modest inhibition of HIV-1 replication of ~26%. However, 2 nM β-estradiol increased the amount of HIV-1 replication in the presence of 50 nM D4T from a baseline of 33% (+/- SE = 5.4) to 74% (+/- SE = 5.4) of control virus levels in the absence of drug. Both results were statistically highly significant (p < 0.001). β-estradiol did not increase the replication of a D4T-resistant strain of HIV in the presence of D4T. The effects were unlikely to be due to general cell inhibition or toxicity because these concentrations of drug and hormone cause no cytotoxicity in PBL as measured by trypan blue exclusion. Conclusion β-estradiol inhibited both HIV-1 replication in primary human PBL and the antiretroviral efficacy of D4T in PBL cultures. To optimize antiretroviral drug therapy, it may be necessary to monitor patient hormonal status.

In the face of increasing environmental pressures, environmentally friendly behaviour can help companies achieve truly sustainable growth. The issue of how to promote environmental behaviour among employees is a new challenge for leaders. However, studies do not systematically reveal the mechanisms of the effects of self-sacrificial leadership on employees' organisational citizenship behaviour for the environment (OCBE). Based on social learning theory and the attitude-behaviour-context model, we investigated the impact of self-sacrificial leadership on employees' OCBE by focusing on the mediating role of the corporate social responsibility (CSR) as perceived by employees, and the moderating role of the pro-environmental organisational climate (PEOC). The results of a field survey of 461 employees (small- and medium-sized enterprises) in China indicate that self-sacrificial leadership was positively related to employees' OCBE; this relationship was partially mediated by employees' perception of CSR. Moreover, PEOC strengthened the effect of employees' perceived CSR on OCBE, and the mediating effect of employees' perceived CSR on the relationship between self-sacrificial leadership and OCBE. Our findings not only help scholars understand the mechanism of the effect of self-sacrificial leadership on employees' OCBE, but also provide insights for recommending integrated management models, social responsibility, and environmental protection.

West Nile virus (WNV) was detected in the United States in 1999, has reoccurred every summer since, and has become endemic. Transfusion transmission was documented in 2002, and screening of blood donations for WNV began in 2003. We investigated genetic variation of WNV in human isolates obtained from specimens collected from 30 infected blood donors who tested positive for WNV RNA during 2002-2005. Complete genomic sequences of 8 isolates and structural gene sequences from 22 additional isolates were analyzed. We found some genetic diversity in isolates from different geographic regions and genetic divergence from reported sequences from epidemics in 1999-2001. Nucleotide divergence of structural genes showed a small increase from 2002 (0.18%) to 2005 (0.37%), suggesting absence of strong selective pressure and limited genetic evolution of WNV during that period. Nevertheless, WNV has continued to diverge from precursor isolates as geographic distribution of the virus has expanded.

Background. West Nile virus (WNV) is endemic in the United States. It is transmissible by blood transfusion, and the nation's blood supply is currently screened for WNV. Documented transmission of WNV infection through red blood cell (RBC) units in which the plasma co-component had a low viral load could be explained, in at least 1 instance, by cell-association of WNV; in this case, the RBC unit was released as negative by minipool nucleic acid testing (NAT) performed on plasma but was intermittently NAT-positive when subsequently tested as an individual sample. We hypothesized that a proportion of WNV bound to blood cells and was not measured by NAT performed on plasma samples. We have investigated whether WNV binds to RBCs, leading to reduction of WNV RNA detection by NAT performed on plasma samples.Methods. Equal volumes of leukoreduced RBCs and their corresponding plasma components from 20 blood donors with NAT results that were positive for WNV were tested in 5 replicates by reverse-transcriptase polymerase chain reaction TaqMan for WNV. In addition, aliquots from 8 of the RBC units were tested by infectivity assays using Vero cells.Results. The reverse-transcriptase polymerase chain reaction TaqMan assay showed that the viral load in the RBC components exceeded that in the corresponding plasma units by 1 order of magnitude. In addition, viruses associated with the RBCs were infectious in Vero cell cultures.Conclusions. These observations reinforce the notion that extraction of viral RNA from whole blood could improve assay sensitivity for blood donor screening and further reduce the residual risk of WNV transmission through transfusion.

Several diagnostic assays for the detection of HIV infection have been approved and licensed by the FDA for blood donor screening. However, the performance of these assays is unknown when testing genetically divergent blood specimens. To evaluate the performance of these assays with diverse HIV strains, we chose to study specimens collected from blood donors in Cameroon where genetic diversity and recombinant variants are prevalent. In this study, we tested 240 human plasma specimens collected from two blood centers in Cameroon. These samples were screened initially in Cameroon for antibody to HIV using a rapid assay. We also performed sequencing to determine subtype. Our evaluation has demonstrated that HIV infection in most HIV plasma samples could be detected by most of the US FDA licensed diagnostic assays. With the exception of a few specimens, HIV-1 p24 antigen was not detected in any of the samples. In addition, some nucleic acid tests (NAT) assays were not able to detect a few serologic reactive samples and all new variants including some CRF02_AG variants.

Vaccination against influenza has been reported to interfere with the performance of assays used to test donated blood, giving false-positive results for various disease markers.1-3 Current regulations require blood donors to be deferred indefinitely if their donated blood tests reactive for the presence of markers for human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis B virus (HBV), or hepatitis C virus (HCV). More than 30 years ago, smallpox vaccination was required in the United States and was usually given as a condition of entry into public schools. Thus, smallpox vaccinations were administered many years before recipients became eligible blood donors and before current donor screening assays were implemented. As a result, no information is available on the incidence of false-positive reactions for infectious disease markers after vaccination with live vaccinia virus. In the following report, we describe a study of the potential interference of smallpox vaccination on the results of testing donated blood for infectious disease markers using currently licensed serologic assays. We collected blood from 75 volunteers who participated in two ongoing clinical trials for smallpox vaccines. All subjects had received a licensed live vaccinia vaccine (Dryvax, Wyeth, Collegeville, PA). Details of vaccinee demographics and vaccine strain derivations were not provided to us. We collected ethylenediaminetetraacetate- or citrate-anticoagulated venous blood on Days 0 (before vaccination), 3, 7, 14, 28, and 56 after vaccination. Blood samples were shipped to our laboratory on wet ice. Plasma was separated using standard separation methods and stored at −70°C until tested. We collected a total of 356 plasma samples from participants in the two clinical studies. There were 216 samples from 45 individuals from Study A and 140 samples from 30 individuals from Study B. Study A samples were tested for HIV and HTLV markers with Abbott HIV-1 antigen (enzyme immunoassay [EIA]), Abbott HIV-1 and -2 (EIA), Abbott HTLV-I and -II (EIA), Bio-Rad HIV-1 (EIA), Bio-Rad HIV-2 (EIA), Bio-Rad HIV-1 and -2 (EIA), bioMérieux HIV-1 (EIA), bioMérieux HTLV-I and -II (EIA), and the Coulter p24 antigen (EIA). Assays used for testing HBV markers were Abbott AUSZYME (EIA), Abbott CORZYME (EIA), Abbott AUSAB (EIA), Ortho HBc (EIA), Ortho HBsAg (EIA), and Bio-Rad HBsAg (EIA). Assays for HCV markers were Ortho third-generation HCV (EIA) and Abbott second-generation HCV (EIA). Study B samples were tested for HIV and HTLV markers only, because of insufficient sample. No false-positive reactions for hepatitis B or C markers were observed with postsmallpox vaccination samples from either study. Of 45 prevaccination samples from Study A, 27 were repeatedly reactive for the presence of anti-HBs by the Abbott AUSAB assay. These individuals had been vaccinated recently against hepatitis B. These samples did not react when tested by all other hepatitis assays listed above. Samples from three vaccinees gave false-positive results when tested by certain HIV and HTLV assays. Plasma samples collected from two different vaccinees in Study A on Days 28 and 56 demonstrated cross-reactivity with the Bio-Rad HIV-1 and -2 antibody assay. Additional testing by Western blot (Bio-Rad Laboratories Blood Virus Division, Redmond, WA) yielded negative results. Also, plasma from one subject in Study B showed reactivity on Days 3, 8, 15, and 28 with the Bio-Rad HIV-2 antibody test kit. These samples were tested using the Bio-Rad HIV-1 Western blot and gave negative results. Confirmation of HIV-2 antibodies was not feasible because licensed HIV-2 supplemental tests are currently not available. This study involved a limited number of vaccinees because of concerns regarding the safety of live vaccinia virus as an immunogen at the time the studies were conducted. We do not have information about the effectiveness of the vaccine preparations used. We are not aware of serologic tests for vaccinia antibody, and questions have been raised as to the degree of correlation between the presence of antibodies and protection. Safety concerns have prompted the development of new vaccinia strains and alternative smallpox immunogens not involving live virus. Extrapolating from the incidence of cross-reactivity observed with these HIV, HTLV, HBV, and HCV marker assays, we estimate a false-positivity rate that could potentially defer as many as 2 percent of vaccinated donors if their blood is tested by the Bio-Rad HIV-1 and -2 or HIV-2 assays. Of 356 samples, 6 showed consistent low-level reactivity with the two licensed HIV antibody assays, both assays containing HIV-2 antigens. The reason for this low level of cross-reactivity observed with the 6 samples is unknown and warrants further investigation. The question of cross-reactivity caused by smallpox immunization will need to be revisited, however, as new and different virus preparations become available. The number of samples in this study is not sufficient for an accurate estimate of the number of donors who would be deferred, should mass vaccination with live Dryvax-derived vaccinia become necessary. Our results indicate, however, that the likelihood of an acute shortage of transfusable blood and blood products due to false-positive reactions as a result of smallpox vaccination would be low. We thank the sponsors and participants of the vaccine trials, without whom this study would not have been feasible. We also acknowledge the Office of Research Development and Coordination of HHS for partial funding of this study.

A potential public health concern is the reported detection of the human T-lymphotropic virus (HTLV) tax gene in the lymphocytes of up to 11% of a low-risk group of New York City blood donors (NYBD). This study aimed to independently confirm the prevalence of HTLV tax sequences in 293 NYBD. All NYBD tested negative for antibodies to HTLV types 1 and 2 and HTLV Tax. HTLV tax sequences were not detected in the NYBD lymphocytes. These data demonstrate the lack of HTLV-1 tax in this group of NYBD at low risk for HTLV infection.