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An abstract of the research paper "Antibody responses to V2 loop are induced by CRF01_A E and not Clade B envelopes," by N. Karasawas and colleagues is presented.

Sexual transmission is the principal driver of the human immunodeficiency virus (HIV) pandemic. Understanding HIV vaccine-induced immune responses at mucosal surfaces can generate hypotheses regarding mechanisms of protection, and may influence vaccine development. The RV144 (ClinicalTrials.gov NCT00223080) efficacy trial showed protection against HIV infections but mucosal samples were not collected, therefore, the contribution of mucosal antibodies to preventing HIV-1 acquisition is unknown. Here, we report the generation, magnitude and persistence of antibody responses to recombinant gp120 envelope and antigens including variable one and two loop scaffold antigens (gp70V1V2) previously shown to correlate with risk in RV144. We evaluated antibody responses to gp120 A244gD and gp70V1V2 92TH023 (both CRF01&#95;AE) and Case A2 (subtype B) in cervico-vaginal mucus (CVM), seminal plasma (SP) and rectal secretions (RS) from HIV-uninfected RV144 vaccine recipients, who were randomized to receive two late boosts of ALVAC-HIV/AIDSVAX®B/E, AIDSVAX®B/E, or ALVAC-HIV alone at 0 and 6 months. Late vaccine boosting increased IgG geometric mean titers (GMT) to gp120 A244gD in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM (28 and 17 fold, respectively), followed by SP and RS. IgG to gp70V1V2 92TH023 increased in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM (11-17 fold) and SP (2 fold) two weeks post first boost. IgG to Case A2 was only detected in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM. Mucosal IgG to gp120 A244gD (CVM, SP, RS), gp70V1V2 92TH023 (CVM, SP), and Case A2 (CVM) correlated with plasma IgG levels (p<0.001). Although the magnitude of IgG responses declined after boosting, anti-gp120 A244gD IgG responses in CVM persisted for 12 months post final vaccination. Further studies in localization, persistence and magnitude of envelope specific antibodies (IgG and dimeric IgA) in anogenital secretions will help determine their role in preventing mucosal HIV acquisition. more...

Background: The development of an effective HIV-1 vaccine is critical to control the pandemic. A prime-boost HIV-1 vaccine trial assessing safety and immunogenicity was conducted in Thailand as part of an evaluation of candidate regimens for a phase 3 efficacy trial., Methods: ALVAC-HIV (vCP1521), expressing circulating recombinant form 01&#95;AE (CRF01&#95;AE) gp120/subtype B LAI and subtype B Gag/Protease boosted with recombinant envelope oligomeric CRF01&#95;AE gp160 (ogp160) or bivalent CRF01&#95;AE/subtype B gp120 CM235/SF2, was evaluated in a phase 1/II trial of 130 HIV-negative Thai adults., Results: One hundred forty volunteers were enrolled, and 130 completed all safety and immunogenicity visits. Reactogenicity was common but generally mild, and there was no significant difference in the adverse event rate between vaccine and placebo recipients (P = 0.26). There were 7 serious adverse events during the follow-up period, none of which were vaccine related. Cumulative HIV-specific, CD8-mediated, cytotoxic T-lymphocyte responses were observed in 11 (25%) of 44 subjects who received ALVAC boosted by bivalent gp120 and in 5 (11%) of 45 subjects who received ALVAC boosted by ogp160, but these differences were not statistically significant compared with those in placebo recipients (P = 0.62 and P = 0.37, respectively). HIV-specific lymphoproliferative responses were detected in 84% of subunit-boosted vaccine recipients and in 10% of placebo recipients. Neutralizing antibody responses to CRF01&#95;AE and subtype B laboratory strains were seen in 95% of ogp160-boosted and 100% of gp120 B/E-boosted vaccinees, respectively., Conclusions: These 2 different prime-boost regimens seem to be safe and displayed cell-mediated immune responses consistent with those in other trials of canarypox vectors. more...

ALVAC-HIV (vCP1521) and AIDSVAX B/E were evaluated in a phase 1/2 trial of human immunodeficiency virus (HIV)-negative Thai adults. Of 133 volunteers enrolled, 122 completed the trial. There were no serious vaccine-related adverse events, nor were there intercurrent HIV infections. Lymphoproliferative responses to glycoprotein 120 E were induced in 63% of the volunteers, and HIV-specific CD8 cytotoxic T lymphocyte responses were induced in 24%. Antibody responses increased in frequency and magnitude in association with the dose level of AIDSVAX B/E. Binding and neutralizing antibodies to the MN strain were induced in 100% and 98%, respectively, of the volunteers receiving 600 microg of AIDSVAX B/E, and such antibodies to E strains were induced in 96% and 71%, respectively, of these volunteers. This vaccine combination was well tolerated and was immunogenic, meeting milestones for advancement to phase 3 evaluation. more...

The inability to distinguish recrudescent Plasmodium falciparum infections (treatment failures) from reinfections (new infections) is an important impediment to the evaluation of antimalarial treatment regimens. Ten paired primary and recrudescent isolates collected near the Thai-Cambodian border were analyzed by restriction fragment length polymorphism (RFLP) and by polymerase chain reaction (PCR) genotyping of the genes encoding the following proteins: circumsporozite (CS) protein, erythrocyte binding antigen (EBA)-175, ring-infected erythrocyte surface antigen (RESA), merozoite surface protein-1 (MSP-1), and MSP-2. Both methods demonstrated that the fingerprint pattern of each recrudescent isolate was identical to or was contained within the pattern of the primary isolate. Each recrudescent isolate was unique when compared with the other nine primary isolates. Typing by PCR was more sensitive for the detection of multiclone infections and could be performed with small volumes of whole blood. The PCR genotyping could be a practical method for distinguishing a recrudescent from a new infection when treatment studies are conducted in areas with active malaria transmission. more...

Plasmodium falciparum parasites develop in the liver before being released into the bloodstream, where they exert the potentially lethal effects characteristic of malaria. Our understanding of the hepatic phase of the life cycle is limited by the parasite's requirement for fresh human liver cells in which to mature. In this work, liver parasites completed their development within a Thai human hepatoma cell line (HHS-102), and the presence of ring-form parasites in erythrocytes overlying the liver cell culture confirmed that an entire liver cycle was completed, culminating in the production of viable blood-stage parasites. The HHS-102 cell line allows investigation of the undefined liver stage of falciparum malaria previously unavailable in the laboratory. more...

Crude antigens prepared from the infective stage larvae of Trichinella spiralis were used for antibody detection by indirect ELISA and Western blotting in serum samples taken from trichinellosis patients and from normal, parasite-free controls. The serum specimens were collected from acute ill, symptomatic patients on the first day of treatment (Day 0), and then two months (M2) and 4 months (M4) later. The sensitivities of the indirect ELISA and Western blotting on Day 0 were 81% and 92%, respectively. Both tests were 100% sensitive for M2 and M4 serum samples. Every serum sample from the parasite-free controls tested negative by both immunological assays, indicating 100% specificity. Crude somatic antigens can therefore be used for the early detection of human trichinellosis (acute trichinellosis). more...

Canalicular and mitochondrial membranes were investigated as early foci of hepatocyte injury in fed and fasted male Sprague-Dawley rats given 50 mg of 1,1-dichloroethylene (DCE)/kg. Staining of the bile canaliculi localized enzymes, leucine aminopeptidase (LAP), and Mg++-dependent ATPase (Mg++-ATPase), was examined by histochemistry in frozen sections. Mitochondrial membrane enzymes, including succinate dehydrogenase, also were examined by histochemistry. Staining of two monoclonal antibodies, C-1 and 9-B1, whose binding is localized in the bile canalicular region, was examined by immunofluorescence in frozen sections. Fasted rats treated with DCE developed moderate liver damage by 4 hours as evidenced by increases in serum transaminase and bilirubin, whereas fed rats developed only slight cell damage. Centrolobular loss of immunocytochemical and histochemical canalicular staining, especially for C-1 and Mg++-ATPase, was evident as early as 1 hour after DCE and was striking by 2 hours in both fed and fasted rats. Decreases in mitochondrial enzymes were not evident histochemically in fed animals at any time after DCE and were found only at the later times in fasted animals given the toxin. Thus, DCE administration to fed rats provides a new model system of selective bile canaliculi injury. more...

Different lineages of hepatocellular carcinoma (HCC) were identified by the application of selected monoclonal antibodies to the study of the sequential histopathological changes which occurred during two regimens of chemical carcinogenesis in the rat. One regimen, that of Solt-Farber, caused prominent oval cell proliferation and large multiple neoplastic nodules, and the other regimen, continuous administration of diethylnitrosamine, produced minimal oval cell proliferation and a few small nodules. However, both regimens produce HCC in most exposed rats. Three monoclonal antibodies to liver cells, OV-6, H-4, and T-6, were selected on the basis of different tissue staining. OV-6 stains the cytoskeleton of bile duct cells, oval cells, and HCC but not that of hepatocytes. H-4 stains the cytoplasm of hepatocytes but of not hepatomas. T-6 stains the cytoskeleton of HCC only. In the Solt-Farber model, the monoclonal antibodies identified groups of hepatocytes within the persistent neoplastic nodules which had acquired the OV-6 epitope and had lost the H-4 epitope. HCC derived from this regimen had the same staining pattern, suggesting that the OV-6 positive H-4 negative hepatocytes were the precursors of the HCC. The presence within the nodules of oval cells, atypical duct structures, cells intermediate between duct cells and hepatocytes, and nodular hepatocytes all containing the OV-6 epitope raises the possibility that any of these cell types could serve as the precursor of the OV-6 positive hepatocytes that arose within the nodule. In the continuous diethylnitrosamine regimen a different staining pattern was seen. T-6 positive hepatocytes first appeared in periportal areas by the 5th week. These cells increased in numbers during the later weeks and with rare exceptions neither acquired the OV-6 epitope nor completely lost the H-4 epitope. Most HCC derived by the continuous diethylnitrosamine regimen were T-6 positive and OV-6 negative, suggesting a direct lineage from the periportal T-6 positive hepatocytes. These findings indicate that the lineage and phenotype of chemically induced HCC may vary with the carcinogenic regimen used and that HCC which arise in nodules may originate from cell types other than typical nodular cells. more...