PET/CT Targeted Tissue Sampling Reveals Intravenously Administered HGN194 IgG1 Affects HIV Distribution after Rectal Exposure.

Neutralizing monoclonal antibodies hold great potential for prevention of human immunodeficiency virus (HIV) acquisition. IgG is the most abundant antibody in human serum, has a long half-life, and potent effector functions, making it a prime candidate for an HIV prevention therapeutic. We combined Positron Emission Tomography imaging and fluorescent microscopy of 64Cu-labeled, photoactivatable-green fluorescent protein HIV (PA-GFP-BaL) and fluorescently labeled HGN194 IgG1 to determine whether intravenously instilled IgG influences viral interaction with mucosal barriers and viral penetration in colorectal tissue 2 h after rectal viral challenge. Our results show that IgG1 did not alter the number of virions found throughout the colon or viral penetration into the epithelium of the rectum or descending colon. A minor increase in virions was observed in the transverse colon of IgG1 treated animals. Overall, the number of viral particles found in the mesenteric lymph nodes was low. However, IgG1 administration resulted in a significant reduction of virions found in mesenteric lymph nodes. Taken together, our results show that HGN194 IgG1 does not prevent virions from penetrating into the colorectal mucosa but may perturb HIV virion access to the lymphatic system.

Vaccine priming of rare HIV broadly neutralizing antibody precursors in nonhuman primates.

Germline-targeting immunogens hold promise for initiating the induction of broadly neutralizing antibodies (bnAbs) to HIV and other pathogens. However, antibody-antigen recognition is typically dominated by heavy chain complementarity determining region 3 (HCDR3) interactions, and vaccine priming of HCDR3-dominant bnAbs by germline-targeting immunogens has not been demonstrated in humans or outbred animals. In this work, immunization with N332-GT5, an HIV envelope trimer designed to target precursors of the HCDR3-dominant bnAb BG18, primed bnAb-precursor B cells in eight of eight rhesus macaques to substantial frequencies and with diverse lineages in germinal center and memory B cells. We confirmed bnAb-mimicking, HCDR3-dominant, trimer-binding interactions with cryo-electron microscopy. Our results demonstrate proof of principle for HCDR3-dominant bnAb-precursor priming in outbred animals and suggest that N332-GT5 holds promise for the induction of similar responses in humans.

An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques.

The systemic nature of SARS-CoV-2 infection is highly recognized, but poorly characterized. A non-invasive and unbiased method is needed to clarify whole body spatiotemporal dynamics of SARS-CoV-2 infection after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of three rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we track the 64Cu-labelled CR3022-F(ab')2 probe targeting the spike protein of SARS-CoV-2 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Using this method, we uncovered differences in lung pathology between infection with the WA1 isolate and the delta variant, which were readily corroborated through computed tomography scans. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites.

An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques.

The systemic nature of SARS-CoV-2 infection is highly recognized, but poorly characterized. A non-invasive and unbiased method is needed to clarify whole body spatiotemporal dynamics of SARS-CoV-2 infection after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of three rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we track the 64Cu-labelled CR3022-F(ab')2 probe targeting the spike protein of SARS-CoV-2 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Using this method, we uncovered differences in lung pathology between infection with the WA1 isolate and the delta variant, which were readily corroborated through computed tomography scans. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites.

Effective Prophylaxis of COVID-19 in Rhesus Macaques Using a Combination of Two Parenterally-Administered SARS-CoV-2 Neutralizing Antibodies.

SARS-CoV-2 is a respiratory borne pathogenic beta coronavirus that is the source of a worldwide pandemic and the cause of multiple pathologies in man. The rhesus macaque model of COVID-19 was utilized to test the added benefit of combinatory parenteral administration of two high-affinity anti-SARS-CoV-2 monoclonal antibodies (mAbs; C144-LS and C135-LS) expressly developed to neutralize the virus and modified to extend their pharmacokinetics. After completion of kinetics study of mAbs in the primate, combination treatment was administered prophylactically to mucosal viral challenge. Results showed near complete virus neutralization evidenced by no measurable titer in mucosal tissue swabs, muting of cytokine/chemokine response, and lack of any discernable pathologic sequalae. Blocking infection was a dose-related effect, cohorts receiving lower doses (6, 2 mg/kg) resulted in low grade viral infection in various mucosal sites compared to that of a fully protective dose (20 mg/kg). A subset of animals within this cohort whose infectious challenge was delayed 75 days later after mAb administration were still protected from disease. Results indicate this combination mAb effectively blocks development of COVID-19 in the rhesus disease model and accelerates the prospect of clinical studies with this effective antibody combination.

Development of an In Vivo Probe to Track SARS-CoV-2 Infection in Rhesus Macaques.

Infection with the novel coronavirus, SARS-CoV-2, results in pneumonia and other respiratory symptoms as well as pathologies at diverse anatomical sites. An outstanding question is whether these diverse pathologies are due to replication of the virus in these anatomical compartments and how and when the virus reaches those sites. To answer these outstanding questions and study the spatiotemporal dynamics of SARS-CoV-2 infection a method for tracking viral spread in vivo is needed. We developed a novel, fluorescently labeled, antibody-based in vivo probe system using the anti-spike monoclonal antibody CR3022 and demonstrated that it could successfully identify sites of SARS-CoV-2 infection in a rhesus macaque model of COVID-19. Our results showed that the fluorescent signal from our antibody-based probe could differentiate whole lungs of macaques infected for 9 days from those infected for 2 or 3 days. Additionally, the probe signal corroborated the frequency and density of infected cells in individual tissue blocks from infected macaques. These results provide proof of concept for the use of in vivo antibody-based probes to study SARS-CoV-2 infection dynamics in rhesus macaques.

Effect of HIV Antibody VRC01 on Viral Rebound after Treatment Interruption.

BACKGROUND: The discovery of potent and broadly neutralizing antibodies (bNAbs) against human immunodeficiency virus (HIV) has made passive immunization a potential strategy for the prevention and treatment of HIV infection. We sought to determine whether passive administration of VRC01, a bNAb targeting the HIV CD4-binding site, can safely prevent or delay plasma viral rebound after the discontinuation of antiretroviral therapy (ART). METHODS: We conducted two open-label trials (AIDS Clinical Trials Group [ACTG] A5340 and National Institutes of Health [NIH] 15-I-0140) of the safety, side-effect profile, pharmacokinetic properties, and antiviral activity of VRC01 in persons with HIV infection who were undergoing interruption of ART. RESULTS: A total of 24 participants were enrolled, and one serious alcohol-related adverse event occurred. Viral rebound occurred despite plasma VRC01 concentrations greater than 50 µg per milliliter. The median time to rebound was 4 weeks in the A5340 trial and 5.6 weeks in the NIH trial. Study participants were more likely than historical controls to have viral suppression at week 4 (38% vs. 13%, P=0.04 by a two-sided Fisher's exact test in the A5340 trial; and 80% vs. 13%, P<0.001 by a two-sided Fisher's exact test in the NIH trial) but the difference was not significant at week 8. Analyses of virus populations before ART as well as before and after ART interruption showed that VRC01 exerted pressure on rebounding virus, resulting in restriction of recrudescent viruses and selection for preexisting and emerging antibody neutralization-resistant virus. CONCLUSIONS: VRC01 slightly delayed plasma viral rebound in the trial participants, as compared with historical controls, but it did not maintain viral suppression by week 8. In the small number of participants enrolled in these trials, no safety concerns were identified with passive immunization with a single bNAb (VRC01). (Funded by the National Institute of Allergy and Infectious Diseases and others; ACTG A5340 and NIH 15-I-0140 ClinicalTrials.gov numbers, NCT02463227 and NCT02471326 .).

Prescribing physical activity: applying the ACSM protocols for exercise type, intensity, and duration across 3 training frequencies.

When physicians advise patients to attain more physical activity, they usually recommend a walking program. However, in a similar way to no exercise, those embarking on a walking program will typically lose 4 to 6 lb of lean weight and reduce their resting metabolic rate 2% to 3% every decade. These effects may be mitigated by the inclusion of resistance exercise. The American College of Sports Medicine (ACSM) minimum exercise guidelines recommend 20 minutes of aerobic activity 3 days per week, and 1 set (8-12 repetitions) of 8 to 10 resistance exercises to train the major muscle groups 2 days per week. However, large-scale testing of these recommendations in a field setting has been minimal. Men and women between 21 and 80 years (N = 1725) [corrected] participated in a 10-week combined strength and aerobic activity program based on the ACSM protocols for exercise intensity and duration across 3 training frequencies (1, 2, or 3 sessions/week). Across all training frequencies, mean changes included a reduction in body fat of 1.97%, a decrease in fat weight of 1.7 kg, an increase in lean weight of 1.35 kg, a reduction in systolic blood pressure of 3.83 mm Hg, and a reduction in diastolic blood pressure of 1.73 mm Hg. More frequent weekly training sessions were associated with greater improvements in body fat percent, fat weight, and lean weight. Participants responded favorably to the ACSM exercise program with a 91% completion rate and a 95% satisfaction rating. This article presents recommendations for prescribing safe, effective, and time-efficient exercise programs.