Linda Andrus

Protection against Chronic Hepatitis C Virus Infection after Rechallenge with Homologous, but Not Heterologous, Genotypes in a Chimpanzee Model

An open question for hepatitis C virus (HCV) vaccine development is whether the various genotypes of this virus protect against the development of chronic infection after heterologous infection with different genotypes. We approached this question by challenging chimpanzees that had recovered from HCV genotype 1a or 1b infection with 6 heterologous genotypes as well as with a homologous genotype (for chimpanzees originally infected with genotype 1a). All 9 chimpanzees rechallenged with a homologous genotype developed self-limited infections. Of 11 chimpanzees challenged with 100 chimpanzee infectious doses of heterologous genotypes, 6 developed self-limited infections, with peak viral loads in acute-phase serum that were ~5-fold lower than those seen during primary infections. One chimpanzee (which had recovered from genotype 1b infection and was rechallenged with genotype 6a) did not develop viremia but did show an anamnestic cell-mediated immune response after rechallenge. Four of the 11 chimpanzees rechallenged with heterologous genotypes developed chronic infections with the genotypes used for rechallenge. These findings suggest that a universally protective HCV vaccine may need to incorporate epitopes from multiple genotypes.

Lack of Evidence for HIV Type 1-Related SIVcpz Infection in Captive and Wild Chimpanzees (Pan troglodytes verus) in West Africa

Serum from 387 chimpanzees (Pan troglodytes verus), caught in the wild or bred in captivity, was tested for antibody to HIV-1 and HIV-2, using second- and third-generation enzyme immunoassays. Six samples were repeatedly positive; however, only one of these was Western blot positive. Serial sera drawn before and after the Western blot-positive samples were seronegative, and thus we conclude that this sample represented specimen contamination, or mislabeling. Thus, none of the 387 Pan troglodytes verus from West Africa were spontaneously infected with SIVcpz. Chimpanzees are known to be exquisitely susceptible to infection with HIV-1 when experimentally inoculated, and thus our findings suggest that HIV-1-related viruses do not exist in Pan troglodytes verus in the wild. As it has been convincingly shown that SIVcpz exists in wild Pan troglodytes troglodytes in Central Africa, this suggests that HIV-1 arose in Central Africa, but not in West Africa.

Individual Donor Nucleic Acid Amplification Testing for Detection of West Nile Virus

ABSTRACT We have developed an economical, high-throughput nucleic acid amplification test (NAT) for blood-borne viruses, suitable for use in the screening of plasma samples from individual blood donors. This assay system includes a semiautomated procedure, using 96-well glass fiber plates for the extraction of viral nucleic acids from plasma and “universal beacon” technology which permits the detection of all genotypes of highly variable viruses (e.g., human immunodeficiency virus and hepatitis C virus). In this detection system, two fluorescent- detection technologies were employed successfully in a single tube: molecular beacon for West Nile virus (WNV) detection using a 6-carboxyfluorescein fluorophore and TaqMan for internal control detection using a VIC fluorophore. To establish proof of concept, we focused on the development of a robust individual donor NAT for WNV. The assay showed no reactivity to 15 other viruses tested or to 420 blood donor samples from the WNV pre-epidemic season. No cross-contamination was observed on an alternating positive-/negative-well test. The sensitivity (limit of detection, 95%) of the assay for WNV is between 3.79 and 16.3 RNA copies/ml, depending on which material was used as a standard. The assay detected all positive blood donation samples identified by the Roche WNV NAT. The assay can be performed qualitatively for screening and quantitatively for confirmation.

Comparison of two different preparations of HIV immune globulin for efficiency of neutralization of HIV type 1 primary isolates.

The objective of this study was to compare the virus-neutralizing ability of two different preparations of HIV immune globulin (HIVIG) isolated from human plasma units that were selected according to two different criteria. The first preparation, designated NYBC-HIVIG, was isolated from plasmas with high neutralizing antibody titers against HIV-1. The second preparation, designated NABI-HIVIG, was isolated from plasma with high titers of antibody to the HIV-1 p24 antigen. A panel of primary HIV-1 isolates was phenotypically characterized by their ability to induce syncytia in CEM-SS cells. Neutralization of this panel of primary isolates by the two HIVIG preparations was assessed in HeLa-MAGI-CCR5 cells, utilizing a luminescence-based assay. In addition, the reactivities of these two preparations with a panel of HIV-1 gp120 proteins, V3 loop peptides, and HIV-1 p24 antigen were determined. Both HIVIG preparations were shown to neutralize all virus isolates tested. However, doses of NABI-HIVIG required for 50% virus neutralization were 2.2- to 4.4- fold (mean, 3.2-fold) higher than the required doses of NYBC-HIVIG. Comparative antigen-binding assays showed that, although NABI-HIVIG possessed higher titers of antibody to HIV-1 p24, NYBC-HIVIG generally contained higher titers of antibody to HIV-1 gp120 and V3 peptides. These experiments show that the criteria used for selection of source plasmas for isolation of HIVIG can influence the effective concentration of virus-neutralizing antibody present in the final immunoglobulin preparation, and may determine the doses required for clinical efficacy.