Vaccine Efficacy of ALVAC-HIV and Bivalent Subtype C gp120-MF59 in Adults

BACKGROUND

A safe, effective vaccine is essential to eradicating human immunodeficiency virus (HIV) infection. A canarypox-protein HIV vaccine regimen (ALVAC-HIV plus AIDSVAX B/E) showed modest efficacy in reducing infection in Thailand. An analogous regimen using HIV-1 subtype C virus showed potent humoral and cellular responses in a phase 1-2a trial in South Africa. Efficacy data and additional safety data were needed for this regimen in a larger population in South Africa.

METHODS

In this phase 2b-3 trial, we randomly assigned 5404 adults without HIV-1 infection to receive the vaccine (2704 participants) or placebo (2700 participants). The vaccine regimen consisted of injections of ALVAC-HIV at months 0 and 1, followed by four booster injections of ALVAC-HIV plus bivalent subtype C gp120-MF59 adjuvant at months 3, 6, 12, and 18. The primary efficacy outcome was the occurrence of HIV-1 infection from randomization to 24 months.

RESULTS

In January 2020, prespecified criteria for nonefficacy were met at an interim analysis; further vaccinations were subsequently halted. The median age of the trial participants was 24 years; 70% of the participants were women. The incidence of adverse events was similar in the vaccine and placebo groups. During the 24-month follow-up, HIV-1 infection was diagnosed in 138 participants in the vaccine group and in 133 in the placebo group (hazard ratio, 1.02; 95% confidence interval, 0.81 to 1.30; P = 0.84).

CONCLUSIONS

The ALVAC-gp120 regimen did not prevent HIV-1 infection among participants in South Africa despite previous evidence of immunogenicity. (HVTN 702 ClinicalTrials.gov number, NCT02968849.).

Benign ethnic neutropenia in a South African population, and its association with HIV acquisition and adverse event reporting in an HIV vaccine clinical trial

Benign ethnic neutropenia (BEN) is defined as a neutrophil count of <1.5×10⁹ cells/L in healthy individuals and is more common in populations of certain ethnicities, e.g. African or Middle Eastern ethnicity. Neutrophil values are commonly included in eligibility criteria for research participation, but little is known about the relationship between BEN, HIV acquisition, and the occurrence of adverse events during clinical trials. We investigated these relationships using data from an HIV vaccine efficacy trial of healthy adults from 5 South African sites. We analysed data from the double-blind, placebo-controlled, randomized trial HVTN 503, and its follow-on study HVTN 503-S to assess the prevalence of BEN, its association with HIV infection, and adverse event reporting. These data were then compared with a time- and age-matched, non-pregnant cohort from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007–2008 in the United States (US). The 739 South African participants had a median age of 22.0 years (interquartile range = 20–26) and 56% (n = 412) were male. Amongst the US cohort of 845 participants, the median age was 26 (IQR: 21–30) and the majority (54%, 457/745) were also male. BEN was present at enrolment in 7.0% (n = 52) of South African participants (6% in the placebo group versus 8% in the vaccine group); 81% (n = 42) of those with BEN were male. Pretoria North had the highest prevalence of BEN (11.6%, 5/43), while Cape Town had the lowest (0.7%, 1/152). Participants with BEN had a lower median neutrophil count (1.3 vs. 3.2x10⁹ cells/L; p<0.001) and BMI (20.8 vs. 22.3 kg/m²; p<0.001) when compared to those without BEN. A greater proportion of Black South Africans had neutrophil counts <1.5×10⁹ cells/L compared to US non-Hispanic Whites from the NHANES cohort (7% [52/739] vs. 0.6% [3/540]; p<0.001). BEN did not increase the odds for HIV infection (adjusted odds ratio [aOR]: 1.364, 95% confidence interval [95% CI]: 0.625–2.976; p = 0.4351). However, female gender (aOR: 1.947, 95% CI: 1.265–2.996; p = 0.0025) and cannabis use (aOR: 2.192, 95% CI: 1.126–4.266; p = 0.0209) increased the odds of HIV acquisition. The incidence rates of adverse events were similar between participants in the placebo group with BEN, and those without: 12.1 (95% CI: 7.3–20.1) vs. 16.5 (95% CI: 14.6–18.7; p = 0.06) events per 100 person-years (py) were noted in the infections and infestations system organ class, respectively. The vaccine group had an event incidence rate of 19.7 (95% CI: 13.3–29.2) vs. 14.8 (95% CI: 13.0–16.8; p = 0.07) events per 100py in the group with, and without BEN, respectively. BEN is more prevalent in Black South Africans compared to US Non-Hispanic Whites. Our data do not support excluding populations from HIV vaccine trials because of BEN. BEN was not associated with increased risk for HIV infection or Adverse events on a vaccine trial. Predictors of HIV infection risk were females and cannabis use, underlying the continued importance of prevention programmes in focusing on these populations.

Poststudy Point-of-Care Oral Fluid Testing in Human Immunodeficiency Virus-1 Vaccinees

Background

Experimental human immunodeficiency virus (HIV)-1 vaccines frequently elicit antibodies against HIV-1 that may react with commonly used HIV diagnostic tests, a phenomenon known as vaccine-induced seropositivity/seroreactivity (VISP/VISR). We sought to determine, under clinic conditions, whether a patient-controlled HIV test, OraQuick ADVANCE Rapid HIV-1/2 Antibody Test, detected HIV-1 vaccine-induced antibodies.

Methods

Plasma assessment of HIV-1 cross-reactivity was examined in end-of-study samples from 57 healthy, HIV-uninfected participants who received a candidate vaccine that has entered Phase 2B and 3 testing. We also screened 120 healthy, HIV-uninfected, unblinded HIV-1 vaccine participants with VISP/VISR for an assessment using saliva. These participants came from 21 different parent vaccine protocols representing 17 different vaccine regimens, all of which contained an HIV-1 envelope immunogen. OraQuick ADVANCE was compared with results from concurrent blood samples using a series of commercial HIV screening immunoassays.

Results

Fifty-seven unique participant plasma samples were assayed in vitro, and only 1 (1.8%) was reactive by OraQuick ADVANCE. None of the 120 clinic participants (0%; 95% confidence interval, 0% to 3.7%) tested positive by OraQuick ADVANCE, and all were confirmed to be uninfected by HIV-1 viral ribonucleic acid testing. One hundred eighteen of the 120 (98.3%) participants had a reactive HIV test for VISP/VISR: 77 (64%) had at least 1 reactive fourth-generation HIV-1 diagnostic test (P < .0001 vs no reactive OraQuick ADVANCE results), and 41 (34%) only had a reactive test by the less specific third-generation Abbott Prism assay.

Conclusions

These data suggest that this widely available patient-controlled test has limited reactivity to HIV-1 antibodies elicited by these candidate HIV-1 vaccines.

Experimental exploration of the amphoteric defect model by cryogenic ion irradiation of a range of wide band gap oxide materials

The evolution of electrical resistance as function of defect concentration is examined for the unipolarn-conducting oxides CdO,β-Ga₂O₃, In₂O₃, SnO₂and ZnO in order to explore the predictions of the amphoteric defect model. Intrinsic defects are introduced by ion irradiation at cryogenic temperatures, and the resistance is measured in-situ by current-voltage sweeps as a function of irradiation dose. Temperature dependent Hall effect measurements are performed to determine the carrier concentration and mobility of the samples before and after irradiation. After the ultimate irradiation step, the Ga₂O₃and SnO₂samples have both turned highly resistive. In contrast, the In₂O₃and ZnO samples are ultimately found to be less resistive than prior to irradiation, however, they both show an increased resistance at intermediate doses. Based on thermodynamic defect charge state transitions computed by hybrid density functional theory, a model expanding on the current amphoteric defect model is proposed.

Antigenic competition in CD4+ T cell responses in a randomized, multicenter, double-blind clinical HIV vaccine trial

T cell responses have been implicated in reduced risk of HIV acquisition in uninfected persons and control of viral replication in HIV-infected individuals. HIV Gag-specific T cells have been predominantly associated with post-infection control, whereas Env antigens are the target for protective antibodies; therefore, inclusion of both antigens is common in HIV vaccine design. However, inclusion of multiple antigens may provoke antigenic competition, reducing the potential effectiveness of the vaccine. HVTN 084 was a randomized, multicenter, double-blind phase 1 trial to investigate whether adding Env to a Gag/Pol vaccine decreases the magnitude or breadth of Gag/Pol-specific T cell responses. Fifty volunteers each received one intramuscular injection of 1 × 10¹⁰ particle units (PU) of rAd5 Gag/Pol and EnvA/B/C (3:1:1:1 mixture) or 5 × 10⁹ PU of rAd5 Gag/Pol. CD4⁺ T cell responses to Gag/Pol measured 4 weeks after vaccination by cytokine expression were significantly higher in the group vaccinated without Env, whereas CD8⁺ T cell responses did not differ significantly between the two groups. Mapping of individual epitopes revealed greater breadth of the Gag/Pol-specific T cell response in the absence of Env compared to Env coimmunization. Addition of an Env component to a Gag/Pol vaccine led to reduced Gag/Pol CD4⁺ T cell response rate and magnitude as well as reduced epitope breadth, confirming the presence of antigenic competition. Therefore, T cell-based vaccine strategies should aim at choosing a minimalist set of antigens to reduce interference of individual vaccine components with the induction of the maximally achievable immune response.

Social Impacts Among Participants in HIV Vaccine Trial Network (HVTN) Preventive HIV Vaccine Trials

BACKGROUND

Given the persistent stigma and discrimination against HIV worldwide, preventive HIV vaccine trials face unique challenges. Negative social impacts (NSIs)-problems that HIV vaccine trial participants face in many different spheres of their lives related to trial participation-have received a great deal of attention. Beneficial social impacts (BSIs)-perceived benefits experienced by a participant and resulting from their trial participation-are a critical component of participants' experiences, yet they have received little attention.

SETTING

All HIV Vaccine Trials Network trial participants for whom social impact data were available-8347 participants in 13 countries who enrolled in 48 phase 1, 2a, and 2b trials.

METHODS

A cross-protocol analysis to assess self-reported BSIs and NSIs related to participating in a preventive HIV vaccine trial. Data were obtained from 48 completed HIV Vaccine Trials Network vaccine trials from December 2000 to September 2017.

RESULTS

Overall, 6572 participants (81%) reported at least one BSI, and 686 participants (8%) reported 819 NSI events. Altruism/feeling good helping others was the BSI most often endorsed by study participants (43%), followed by receiving risk-reduction counseling (30%). Most NSI events (81%) were reported by US/Swiss participants, and most (79%) trial-related NSIs were negative reactions from friends, family, and partners. Of the NSIs reported, 7% were considered to have a major impact on the participant's quality of life.

CONCLUSION

Our results underscore the relatively common experiences of BSIs among preventive HIV vaccine trial participants and mirror the results of other studies that find infrequent reports of NSIs.

The ELFIN Mission

The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93^∘ inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime. Its primary science objective is to resolve the mechanism of storm-time relativistic electron precipitation, for which electromagnetic ion cyclotron (EMIC) waves are a prime candidate. From its ionospheric vantage point, ELFIN uses its unique pitch-angle-resolving capability to determine whether measured relativistic electron pitch-angle and energy spectra within the loss cone bear the characteristic signatures of scattering by EMIC waves or whether such scattering may be due to other processes. Pairing identical ELFIN satellites with slowly-variable along-track separation allows disambiguation of spatial and temporal evolution of the precipitation over minutes-to-tens-of-minutes timescales, faster than the orbit period of a single low-altitude satellite (T_orbit ∼ 90 min). Each satellite carries an energetic particle detector for electrons (EPDE) that measures 50 keV to 5 MeV electrons with Δ E/E < 40% and a fluxgate magnetometer (FGM) on a ∼72 cm boom that measures magnetic field waves (e.g., EMIC waves) in the range from DC to 5 Hz Nyquist (nominally) with <0.3 nT/sqrt(Hz) noise at 1 Hz. The spinning satellites (T_spin ∼ 3 s) are equipped with magnetorquers (air coils) that permit spin-up or -down and reorientation maneuvers. Using those, the spin axis is placed normal to the orbit plane (nominally), allowing full pitch-angle resolution twice per spin. An energetic particle detector for ions (EPDI) measures 250 keV - 5 MeV ions, addressing secondary science. Funded initially by CalSpace and the University Nanosat Program, ELFIN was selected for flight with joint support from NSF and NASA between 2014 and 2018 and launched by the ELaNa XVIII program on a Delta II rocket (with IceSatII as the primary). Mission operations are currently funded by NASA. Working under experienced UCLA mentors, with advice from The Aerospace Corporation and NASA personnel, more than 250 undergraduates have matured the ELFIN implementation strategy; developed the instruments, satellite, and ground systems and operate the two satellites. ELFIN's already high potential for cutting-edge science return is compounded by concurrent equatorial Heliophysics missions (THEMIS, Arase, Van Allen Probes, MMS) and ground stations. ELFIN's integrated data analysis approach, rapid dissemination strategies via the SPace Environment Data Analysis System (SPEDAS), and data coordination with the Heliophysics/Geospace System Observatory (H/GSO) optimize science yield, enabling the widest community benefits. Several storm-time events have already been captured and are presented herein to demonstrate ELFIN's data analysis methods and potential. These form the basis of on-going studies to resolve the primary mission science objective. Broad energy precipitation events, precipitation bands, and microbursts, clearly seen both at dawn and dusk, extend from tens of keV to >1 MeV. This broad energy range of precipitation indicates that multiple waves are providing scattering concurrently. Many observed events show significant backscattered fluxes, which in the past were hard to resolve by equatorial spacecraft or non-pitch-angle-resolving ionospheric missions. These observations suggest that the ionosphere plays a significant role in modifying magnetospheric electron fluxes and wave-particle interactions. Routine data captures starting in February 2020 and lasting for at least another year, approximately the remainder of the mission lifetime, are expected to provide a very rich dataset to address questions even beyond the primary mission science objective.

Long-term mucosal T cell activation and homing phenotypes in recipients of an Ad5-vectored HIV vaccine

BACKGROUND

Vaccine-induced mucosal immune responses may be critical for protection against HIV infection, but may also result in short or long-term changes that enhance susceptibility to infection in some individuals, such as those with baseline seroreactivity to vaccine vector antigens. We examined cellular immune responses in blood and gut mucosal tissue roughly two years following vaccination with placebo or the Step study vaccine MRKAd5/HIV-1.

METHODS

Participants vaccinated with either placebo or MRKAd5/HIV-1 during participation in HVTN 071, and HVTN 502/Merck 023 underwent phlebotomy and colonic mucosal biopsies via flexible sigmoidoscopy at two timepoints roughly six months apart. After isolation of mononuclear cells, we compared cellular phenotypes and intracellular cytokine responses in vaccine and placebo recipients with and without baseline serological reactivity to Ad5.

RESULTS

Surface expression of activation and gut-homing markers were elevated on CD4 + and CD8 + gut mucosal mononuclear cells (GMMC) in comparison with PBMC (p < 0.01), but were not significantly affected by baseline Ad5 serostatus or receipt of MRKAd5/HIV-1. ICS responses to stimulation with vaccine antigens were of low frequency and magnitude. Ad5 vector responses were seen in vaccinees and baseline seropositive individuals. CD4 + responses to vector antigens were more common in GMMC than PBMC (p < 0.01) and CD8 + responses to HIV gag insert antigens were more frequent in Ad5 seropositive than Ad5 seronegative individuals (p = 0.03).

CONCLUSION

Vaccination with the Ad5 vectored candidate HIV vaccine MRKAd5/HIV-1 does not lead to long-term changes in the activation state of mucosal CD4 + or CD8 + T lymphocytes regardless of baseline Ad5 serostatus. The findings of this study do not reveal a basis for enhanced susceptibility to HIV infection two years post vaccination.

HIV-1 Vaccine Sequences Impact V1V2 Antibody Responses: A Comparison of Two Poxvirus Prime gp120 Boost Vaccine Regimens

In the RV144 trial, vaccine-induced V1V2 IgG correlated with decreased HIV-1 risk. We investigated circulating antibody specificities in two phase 1 poxvirus prime-protein boost clinical trials conducted in South Africa: HVTN 097 (subtype B/E) and HVTN 100 (subtype C). With cross-subtype peptide microarrays and multiplex binding assays, we probed the magnitude and breadth of circulating antibody responses to linear variable loop 2 (V2) and conformational V1V2 specificities. Antibodies targeting the linear V2 epitope, a correlate of decreased HIV-1 risk in RV144, were elicited up to 100% and 61% in HVTN 097 and HVTN 100, respectively. Despite higher magnitude of envelope-specific responses in HVTN 100 compared to HVTN 097 (p’s < 0.001), the magnitude and positivity for V2 linear epitope and V1V2 proteins were significantly lower in HVTN 100 compared to HVTN 097. Meanwhile, responses to other major linear epitopes including the variable 3 (V3) and constant 5 (C5) epitopes were higher in HVTN 100 compared to HVTN 097. Our data reveal substantial differences in the circulating antibody specificities induced by vaccination in these two canarypox prime-protein boost trials. Our findings suggest that the choice of viral sequences in prime-boost vaccine regimens, and potentially adjuvants and immunogen dose, influence the elicitation of V2-specific antibodies.

Comparison of routine field epidemiology and whole genome sequencing to identify tuberculosis transmission in a remote setting

Yukon Territory (YT) is a remote region in northern Canada with ongoing spread of tuberculosis (TB). To explore the utility of whole genome sequencing (WGS) for TB surveillance and monitoring in a setting with detailed contact tracing and interview data, we used a mixed-methods approach. Our analysis included all culture-confirmed cases in YT (2005-2014) and incorporated data from 24-locus Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats (MIRU-VNTR) genotyping, WGS and contact tracing. We compared field-based (contact investigation (CI) data + MIRU-VNTR) and genomic-based (WGS + MIRU-VNTR + basic case data) investigations to identify the most likely source of each person's TB and assessed the knowledge, attitudes and practices of programme personnel around genotyping and genomics using online, multiple-choice surveys (n = 4) and an in-person group interview (n = 5). Field- and genomics-based approaches agreed for 26 of 32 (81%) cases on likely location of TB acquisition. There was less agreement in the identification of specific source cases (13/22 or 59% of cases). Single-locus MIRU-VNTR variants and limited genetic diversity complicated the analysis. Qualitative data indicated that participants viewed genomic epidemiology as a useful tool to streamline investigations, particularly in differentiating latent TB reactivation from the recent transmission. Based on this, genomic data could be used to enhance CIs, focus resources, target interventions and aid in TB programme evaluation.

Safety and immune responses after a 12-month booster in healthy HIV-uninfected adults in HVTN 100 in South Africa: A randomized double-blind placebo-controlled trial of ALVAC-HIV (vCP2438) and bivalent subtype C gp120/MF59 vaccines

BACKGROUND

HVTN 100 evaluated the safety and immunogenicity of an HIV subtype C pox-protein vaccine regimen, investigating a 12-month booster to extend vaccine-induced immune responses.

METHODS AND FINDINGS

A phase 1-2 randomized double-blind placebo-controlled trial enrolled 252 participants (210 vaccine/42 placebo; median age 23 years; 43% female) between 9 February 2015 and 26 May 2015. Vaccine recipients received ALVAC-HIV (vCP2438) alone at months 0 and 1 and with bivalent subtype C gp120/MF59 at months 3, 6, and 12. Antibody (IgG, IgG3 binding, and neutralizing) and CD4+ T-cell (expressing interferon-gamma, interleukin-2, and CD40 ligand) responses were evaluated at month 6.5 for all participants and at months 12, 12.5, and 18 for a randomly selected subset. The primary analysis compared IgG binding antibody (bAb) responses and CD4+ T-cell responses to 3 vaccine-matched antigens at peak (month 6.5 versus 12.5) and durability (month 12 versus 18) timepoints; IgG responses to CaseA2_gp70_V1V2.B, a primary correlate of risk in RV144, were also compared at these same timepoints. Secondary and exploratory analyses compared IgG3 bAb responses, IgG bAb breadth scores, neutralizing antibody (nAb) responses, antibody-dependent cellular phagocytosis, CD4+ polyfunctionality responses, and CD4+ memory sub-population responses at the same timepoints. Vaccines were generally safe and well tolerated. During the study, there were 2 deaths (both in the vaccine group and both unrelated to study products). Ten participants became HIV-infected during the trial, 7% (3/42) of placebo recipients and 3% (7/210) of vaccine recipients. All 8 serious adverse events were unrelated to study products. Less waning of immune responses was seen after the fifth vaccination than after the fourth, with higher antibody and cellular response rates at month 18 than at month 12: IgG bAb response rates to 1086.C V1V2, 21.0% versus 9.7% (difference = 11.3%, 95% CI = 0.6%-22.0%, P = 0.039), and ZM96.C V1V2, 21.0% versus 6.5% (difference = 14.5%, 95% CI = 4.1%-24.9%, P = 0.004). IgG bAb response rates to all 4 primary V1V2 antigens were higher 2 weeks after the fifth vaccination than 2 weeks after the fourth vaccination: 87.7% versus 75.4% (difference = 12.3%, 95% CI = 1.7%-22.9%, P = 0.022) for 1086.C V1V2, 86.0% versus 63.2% (difference = 22.8%, 95% CI = 9.1%-36.5%, P = 0.001) for TV1c8.2.C V1V2, 67.7% versus 44.6% (difference = 23.1%, 95% CI = 10.4%-35.7%, P < 0.001) for ZM96.C V1V2, and 81.5% versus 60.0% (difference = 21.5%, 95% CI = 7.6%-35.5%, P = 0.002) for CaseA2_gp70_V1V2.B. IgG bAb response rates to the 3 primary vaccine-matched gp120 antigens were all above 90% at both peak timepoints, with no significant differences seen, except a higher response rate to ZM96.C gp120 at month 18 versus month 12: 64.5% versus 1.6% (difference = 62.9%, 95% CI = 49.3%-76.5%, P < 0.001). CD4+ T-cell response rates were higher at month 18 than month 12 for all 3 primary vaccine-matched antigens: 47.3% versus 29.1% (difference = 18.2%, 95% CI = 2.9%-33.4%, P = 0.021) for 1086.C, 61.8% versus 38.2% (difference = 23.6%, 95% CI = 9.5%-37.8%, P = 0.001) for TV1.C, and 63.6% versus 41.8% (difference = 21.8%, 95% CI = 5.1%-38.5%, P = 0.007) for ZM96.C, with no significant differences seen at the peak timepoints. Limitations were that higher doses of gp120 were not evaluated, this study was not designed to investigate HIV prevention efficacy, and the clinical significance of the observed immunological effects is uncertain.

CONCLUSIONS

In this study, a 12-month booster of subtype C pox-protein vaccines restored immune responses, and slowed response decay compared to the 6-month vaccination.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02404311. South African National Clinical Trials Registry (SANCTR number: DOH--27-0215-4796).

AccuMeter noninstrumented quantitative assay of high-density lipoprotein in whole blood

A novel noninstrumented technology (ChemTrak AccuMeter) for the quantitative measurement of analytes in biological fluids was reported at the 1990 Oak Ridge Conference (Clin Chem 1990;36:1591-7). This instrument-free technology has been adapted for the quantitative measurement of high-density lipoprotein (HDL). An in situ lipoprotein separation method has been developed and incorporated into the test for HDL determination. The sensitivity of the assay system has been adjusted so that HDL is measured over a clinically significant range of 250 to 1000 mg/L. This compares to a range of 1000 to 4000 mg/L for the total cholesterol in the earlier reported assay. Like the AccuMeter total cholesterol test, the Accumeter HDL test system is self-contained and consolidates blood separation, lipoprotein separation, and specimen measurement into a single step. The test procedure is simple, and the results are accurate.

3M™ Petrifilm™ Staph Express Count Plate Method for the Enumeration of Staphylococcus aureus in Selected Types of Meat, Seafood, and Poultry: Collaborative Study

The 3M™ Petrifilm™ Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Four foods—cooked, diced chicken; cured ham; smoked salmon; and pepperoni—were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 4 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

VIDAS® Enzyme-Linked Immunofluorescent Assay for Detection of Listeria in Foods: Collaborative Study

The VIDAS LIS method and the traditional culture methods for detection of Listeria species in food were evaluated in a multilaboratory comparative study. The 6 foods tested were either naturally contaminated or inoculated with 3 different concentrations of Listeria. Results for each food and each contamination level with the VIDAS LIS method were as good as or better than those obtained with the traditional culture method. Of 1558 samples tested, 935 were positive: 839 by the VIDAS method and 809 by standard culture methods. Overall false negative rates were 10.3 and 13.5% for the VIDAS LIS and culture methods, respectively. The false positive rate for the VIDAS LIS assay was 1.4% based on 9 VIDAS LIS positive assays that did not confirm positive by isolation of Listeria. The agreement between the VIDAS LIS and culture methods for all samples tested was 86%.

Safety and immunogenicity of a multivalent HIV vaccine comprising envelope protein with either DNA or NYVAC vectors (HVTN 096): a phase 1b, double-blind, placebo-controlled trial

BACKGROUND

Up to now, immunisation regimens that have been assessed for development of HIV vaccines have included purified envelope (Env) protein among the boosting components of the regimen. We postulated that co-administration of Env protein with either a DNA or NYVAC vector during priming would result in early generation of antibody responses to the Env V1/V2 region, which are important markers for effective protection against infection. We aimed to assess the safety and immunogenicity of a multivalent HIV vaccine including either DNA or NYVAC vectors alone or in combination with Env glycoprotein (gp120) followed by a co-delivered NYVAC and Env protein boost.

METHODS

We did a single-centre, double-blind, placebo-controlled phase 1b trial at the Centre Hospitalier Universitaire Vaudois (Lausanne, Switzerland). We included healthy volunteers aged 18-50 years who were at low risk of HIV infection. We randomly allocated participants using computer-generated random numbers to one of four vaccination schedules or placebo (4:1), and within these schedules participants were allocated either active treatment (T1, T2, T3, and T4) or placebo (C1, C2, C3, and C4). T1 consisted of two doses of NYVAC vector followed by two doses of NYVAC vector and gp120 Env protein; T2 comprised four doses of NYVAC vector and gp120 Env protein; T3 was two doses of DNA vector followed by two doses of NYVAC vector and gp120 Env protein; and T4 was two doses of DNA vector and gp120 Env protein followed by two doses of NYVAC vector and gp120 Env protein. Placebo injections were matched to the corresponding active treatment group. Doses were administered by injection at months 0, 1, 3, and 6. Primary outcomes were safety and immunogenicity of the vaccine schedules. Immune response measures included cross-clade and epitope-specific binding antibodies, neutralising antibodies, and antibody-dependent cell-mediated cytotoxicity measured 2 weeks after the month 1, 3, and 6 vaccinations. This trial is registered with ClinicalTrials.gov, NCT01799954.

FINDINGS

Between Aug 23, 2012, and April 18, 2013, 148 healthy adult volunteers were screened for the trial, of whom 96 participants were enrolled. 20 individuals were allocated to each active treatment group (groups T1-4; n=80) and four were assigned to each placebo group (groups C1-4; n=16). Vaccines containing the NYVAC vector (groups T1 and T2) were associated with more frequent severe reactogenicity and more adverse events than were vaccines containing the DNA vector (groups T3 and T4). The most frequent adverse events judged related to study product were lymphadenopathy (n=9) and hypoaesthesia (n=2). Two participants, one in the placebo group and one in the DNA-primed T3 group, had serious adverse events that were judged unrelated to study product. One participant in the T3 group died from cranial trauma after a motor vehicle accident. Across the active treatment groups, IgG responses 2 weeks after the 6-month dose of vaccine were 74-95%. Early administration of gp120 Env protein (groups T2 and T4) was associated with a substantially earlier and higher area under the curve for gp120 Env binding, production of anti-V1/V2 and neutralising antibodies, and better antibody-response coverage over a period of 18 months, compared with vaccination regimens that delayed administration of gp120 Env protein until the 3-month vaccination (groups T1 and T3).

INTERPRETATION

Co-administration of gp120 Env protein components with DNA or NYVAC vectors during priming led to early and potent induction of Env V1/V2 IgG binding antibody responses. This immunisation approach should be considered for induction of preventive antibodies in future HIV vaccine efficacy trials.

FUNDING

National Institutes of Health, National Institute of Allergy and Infectious Diseases, and the Bill & Melinda Gates Foundation.

Updated Methods for the Production of Toxorhynchites rutilus septentrionalis (Diptera, Culicidae) for Use as Biocontrol Agent Against Container Breeding Pest Mosquitoes in Harris County, Texas

The complex biologies of pestiferous mosquito species complicate the development of a single, across the board effective control measure. The use of traditional biological control through predators, parasitoids, and microbes, though part of a multimodal, integrated pest management approach, is scant in current standard mosquito control operations. At this time, traditional, whole organism mosquito biocontrol agents are not commercially available, and if their integration into a release program is desired, they must be developed in-house. The aim of our program was to incorporate releasing natural enemies to disrupt and suppress the target pest mosquito's population by matching the agent with the target's biology, before or concurrent to pesticide use. A current focus is suppressing peridomestic, container breeders of high medical significance, such as Aedes aegypti (Linnaeus), (Diptera, Culicidae) and Aedes albopictus (Skuse) (Diptera, Culicidae), through larval reduction with augmentative releases of laboratory-reared, native mosquito assassins Toxorhynchites rutilus septentrionalis (Dyar & Knab). When raised in communal settings, Tx. rutilus' aggressive feeding behavior and cannibalistic tendencies require an extreme loss tolerance in adult production rates. In addition, offering prey mosquitoes exclusively as Tx. rutilus' juvenile food extends larval development by multiple days. While this may be desirous in the wild, it proves inefficient during production. Here, we provide an individual rearing method as well as an alternative diet protocol, which maximizes the adult yield while achieving quick development.

Abstract P1-15-08: Pathologic complete response rates following neoadjuvant systemic therapy in 794 patients with early breast cancer: The Royal Marsden experience

Background

The presence and extent of residual invasive cancer after neoadjuvant treatment (NACT) is a strong prognostic factor for risk of recurrence, especially in triple-negative (TN) and human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC). Recent advances in the standard-of-care NACT improved pathological complete response (pCR) rates in published clinical trials.

We evaluated the pCR rates, defined as ypT0-is ypN0, in our real-world BC population and in estrogen receptor-positive [ER+] HER2-, HER2+ and TN subgroups and their association with tumour, patients' characteristics and disease-free survival (DFS).

Methods

We retrospectively identified early BC patients receiving NACT between January 2013 and December 2017. Demographics, patient and disease characteristics, pathological responses, toxicities, dose delays and reductions were recorded. Simple statistics, Fisher's exact test, chi-squared method and Cox regression were used as appropriate.

Results

794 patients identified had median age of 50 years (range 24-87) and 93.9% (745 patients) ECOG performance status (PS) 0. 3.0% (24) had clinical stage I disease, 68.0% (540) stage II and 29.0% (230) stage III. 71.0% (564) had grade 3 disease and 91.8% (729) ductal histology. 33.7% (257) had ER+/HER2-, 25.8% (205) had TN and 38.0% (301) HER2+ disease. Overall, 6.8% (54) patients received platinum. 36.6% (291) patients had dose reductions and 24.3% (193) dose delays. Along with NACT, 51.6% (147) of the HER2+ patients received Trastuzumab and Pertuzumab and 48.4% (138) Trastuzumab alone.

pCR rate was 33.1% in the overall population and significantly different in ER+/HER2-, HER2+ and TN subgroups (12.84% versus 52.0% versus 28.43% respectively, p&lt;0.001). pCR was influenced by grade (1: 0%; 2: 24.3%; 3: 36.1%, p 0.005) and histology (ductal: 34.2%; lobular: 10.0%; mixed 25.0%; p 0.01). In the HER2+ subgroup, there was a trend for improved pCR rates for patients receiving Pertuzumab and Trastuzumab (57.0%) versus Trastuzumab alone (51.0%). No statistically significant differences were seen based on patients' characteristics including age and PS or in case of treatment dose reductions and delays. Early discontinuation of NACT was associated with lower pCR rates (20.5% vs 36.29%, p &lt;0.001).

Of interest, pCR rates remained consistent across the period 2013-2017 in the overall population. We observed a trend for improved pCR in the HER2+ (2013: 47.5%; 2014: 44.4%; 2015: 66.7%; 2016: 51.0%; 2017: 51.4%) and TN cohorts (2013: 23.5%; 2014: 25.0%; 2015: 25.0%; 2016: 33.3%; 2017: 34.1%) but not in the ER+/HER2- group.

Median DFS was 83.8 months (95% CI 62.0-NR) in the overall population. Although not reached in the TN cohort, median DFS was different according to disease subgroups (HER2+: 83.78 months; TN: NR; ER+/HER2-: 62.0 months, p &lt;0.0001).

Conclusions

In our analysis pCR rates are consistent with data published in literature and higher in HER2+ and TN disease. The impact of new agents had a relatively low impact on pCR rates in our overall population over the last 5 years, although they produced gradual improvements in the HER2+ and TN subgroups.

Citation Format: Battisti NML, True V, Chaabouni N, Chopra N, Lee K, Shepherd S, Shapira-Rotenberg T, Joshi R, Mohammed K, Allen M, Ring A. Pathologic complete response rates following neoadjuvant systemic therapy in 794 patients with early breast cancer: The Royal Marsden experience [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-08.