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Angiotensin (ANG) type 1A (A[T.sub.1A]) receptor-null (A[T.sub.1A.sup.-/-]) mice exhibit reduced afferent arteriolar (AA) constrictor responses to ANG II compared with wild-type (WT) mice, whereas efferent arteriolar (EA) responses are absent (Harrison-Bernard LM, Cook AK, Oliverio MI, and Coffman TM. Am J Physiol Renal Physiol 284: F538-F545, 2003). In the present study, the renal arteriolar constrictor responses to norepinephrine (NE) and/or ANG II were determined in bloodperfused juxtamedullary nephrons from kidneys of A[T.sub.1A.sup.-/-] A[T.sub.1B] receptor-null ([AT.sub.1B.sup.-/-]), and WT mice. Baseline AA diameter in A[T.sub.1A.sup.-/-] mice was not different from that in WT mice (13.1 [+ or -] 0.9 and 12.6 [+ or -] 0.9 [micro]m, n = 7 and 8, respectively); however, EA diameters were significantly larger (17.3 [+ or -] 1.4 vs. 11.7 [+ or -] 0.4 [micro]m, n = 10 and 8) in A[T.sub.1A.sup.-/-] than in WT mice. Constriction of AA (-40 [+ or -] 8 and -51 [+ or -] 6% at 1 [micro]M NE) and EA (-29 [+ or -] 6 and -38 [+ or -] 3% at 1 [micro]M NE) in response to 0.1-1 [micro]M NE was similar in A[T.sub.1A.sup.-/-] and WT mice. Baseline diameters of AA (13.5 [+ or -] 0.7 and 14.2 [+ or -] 0.9 [micro]m, n = 9 and 10) and EA (15.4 [+ or -] 1.0 and 15.0 [+ or -] 0.7 [micro]m, n = 11 and 9) and ANG II (0.1-10 nM) constrictor responses of AA (-25 [+ or -] 4 and -31 [+ or -] 5% at 10 nM) and EA (-32 [+ or -] 6 and -35 [+ or -] 7% at 10 nM) were similar in A[T.sub.1B.sup.-/-] and WT mice, respectively. ANG II-induced constrictions were eliminated by A[T.sub.1] receptor blockade with 4[micro]M candesartan. Taken together, our data demonstrate that AA and EA responses to NE are unaltered in the absence of A[T.sub.1A] receptors, and ANG II responses remain intact in the absence of A[T.sub.1B] receptors. Therefore, we conclude that A[T.sub.1A] and ATIB receptors are functionally expressed on the AA, whereas the EA exclusively expresses the A[T.sub.1A] receptor. afferent arteriole; efferent arteriole; juxtamedullary nephron; candesartan; norepinephrine

Preclinical mouse models that recapitulate some characteristics of coronavirus disease (COVID-19) will facilitate focused study of pathogenesis and virus--host responses. Human agniotensin-converting enzyme 2 (hACE2) serves as an entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to infect people via binding to envelope spike proteins. Herein we report development and characterization of a rapidly deployable COVID-19 mouse model. C57BL/6J (B6) mice expressing hACE2 in the lung were transduced by oropharyngeal delivery of the recombinant human adenovirus type 5 that expresses hACE2 (Ad5-hACE2).Mice were infected with SARS-CoV-2 at Day 4 after transduction and developed interstitial pneumonia associated with perivascular inflammation, accompanied by significantly higher viral load in lungs at Days 3, 6, and 12 after infection compared with Ad5-empty control group. SARS-CoV-2 was detected in pneumocytes in alveolar septa. Transcriptomic analysis of lungs demonstrated that the infected Ad5-hACE mice had a significant increase in IFN-dependent chemokines Cxcl9 and Cxcl10, and genes associated with effector T-cell populations including Cd3 g, Cd8a, and Gzmb. Pathway analysis showed that several Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were enriched in the data set, including cytokine--cytokine receptor interaction, the chemokine signaling pathway, the NOD-like receptor signaling pathway, the measles pathway, and the IL-17 signaling pathway. This response is correlative to clinical response in lungs of patients with COVID-19. These results demonstrate that expression of hACE2 via adenovirus delivery system sensitized the mouse to SARS-CoV-2 infection and resulted in the development of a mild COVID-19 phenotype, highlighting the immune and inflammatory host responses to SARS-CoV-2 infection. This rapidly deployable COVID-19 mouse model is useful for preclinical and pathogenesis studies of COVID-19. [ABSTRACT FROM AUTHOR]

Angiotensin (ANG) type 1A (AT1A) receptor-null (AT1A-/-) mice exhibit reduced afferent arteriolar (AA) constrictor responses to ANG II compared with wild-type (WT) mice, whereas efferent arteriolar (EA) responses are absent (Harrison-Bernard LM, Cook AK, Oliverio MI, and Coffman TM. Am J Physiol Renal Physiol 284: F538–F545, 2003). In the present study, the renal arteriolar constrictor responses to norepinephrine (NE) and/or ANG I1 were determined in blood-perfused juxtamedullary nephrons from kidneys of AT1A-/-, A1B receptor-null (AT1B-/-), and WT mice. Baseline AA diameter in AT1A-/- mice was not different from that in WT mice (13.1 ± 0.9 and 12.6 ± 0.9 μm, n = 7 and 8, respectively); however, EA diameters were significantly larger (17.3 ± 1.4 vs. 11.7 ± 0.4 μm, n = 10 and 8) in AT1A-/- than in WT mice. Constriction of AA (-40 ± 8 and -51 ± 6% at 1 μM NE) and EA (-29 ± 6 and -38 ± 3% at 1 μM NE) in response to 0.1–1 μM NE was similar in AT1A-/- and WT mice. Baseline diameters of AA (13.5 ± 0.7 and 14.2 ± 0.9 μm, n = 9 and 10) and EA (15.4 ± 1.0 and 15.0 ± 0.7 μm, n = 11 and 9) and ANG II (0.1–10 nM) constrictor responses of AA (-25 ± 4 and -31 ± 5% at 10 nM) and EA (-32 ± 6 and -35 ± 7% at 10 nM) were similar in AT1B-/- and WT mice, respectively. ANG II-induced constrictions were eliminated by AT1 receptor blockade with 4 μM candesartan. Taken together, our data demonstrate that AA and EA responses to NE are unaltered in the absence of AT1A receptors, and ANG II responses remain intact in the absence of AT1B receptors. Therefore, we conclude that AT1A and AT1B receptors are functionally expressed on the AA, whereas the EA exclusively expresses the AT1A receptor. [ABSTRACT FROM AUTHOR]

Simian immunodeficiency virus SIVrcm, which naturally infects red-capped mangabeys (RCMs), is the only SIV that uses CCR2 as its main coreceptor due to the high frequency of a CCR5 deletion in RCMs. We investigated the dynamics of SIVrcm infection to identify specific pathogenic mechanisms associated with this major difference in SIV biology. Four pigtailed macaques (PTMs) were infected with SIVrcm, and infection was monitored for over 2 years. The dynamics of in vivo SIVrcm replication in PTMs was similar to that of other pathogenic and nonpathogenic lymphotropic SIVs. Plasma viral loads (VLs) peaked at 107 to 109 SIVrcm RNA copies/ml by day 10 postinoculation (p.i.). A viral set point was established by day 42 p.i. at 103 to 105 SIVrcm RNA copies/ml and lasted up to day 180 p.i., when plasma VLs decreased below the threshold of detection, with blips of viral replication during the follow-up. Intestinal SIVrcm replication paralleled that of plasma VLs. Up to 80% of the CD4+ T cells were depleted by day 28 p.i. in the gut. The most significant depletion (>90%) involved memory CD4+ T cells. Partial CD4+ T-cell restoration was observed in the intestine at later time points. Effector memory CD4+ T cells were the least restored. SIVrcm strains isolated from acutely infected PTMs used CCR2 coreceptor, as reported, but expansion of coreceptor usage to CCR4 was also observed. Selective depletion of effector memory CD4+ T cells is in contrast with predicted in vitro tropism of SIVrcm for macrophages and is probably due to expansion of coreceptor usage. Taken together, these findings emphasize the importance of understanding the selective forces driving viral adaptation to a new host. [ABSTRACT FROM AUTHOR]

The development of a portfolio of SARS-CoV-2 vaccines to vaccinate the global population remains an urgent public health imperative. Here, we demonstrate the capacity of a subunit vaccine under clinical development, comprising the SARS-CoV-2 Spike protein receptor-binding domain displayed on a two-component protein nanoparticle (RBD-NP), to stimulate robust and durable neutralizing antibody (nAb) responses and protection against SARS-CoV-2 in non-human primates. We evaluated five different adjuvants combined with RBD-NP including Essai O/W 1849101, a squalene-in-water emulsion; AS03, an alpha-tocopherol-containing squalene-based oil-in-water emulsion used in pandemic influenza vaccines; AS37, a TLR-7 agonist adsorbed to Alum; CpG 1018-Alum (CpG-Alum), a TLR-9 agonist formulated in Alum; or Alum, the most widely used adjuvant. All five adjuvants induced substantial nAb and CD4 T cell responses after two consecutive immunizations. Durable nAb responses were evaluated for RBD-NP/AS03 immunization and the live-virus nAb response was durably maintained up to 154 days post-vaccination. AS03, CpG-Alum, AS37 and Alum groups conferred significant protection against SARS-CoV-2 infection in the pharynges, nares and in the bronchoalveolar lavage. The nAb titers were highly correlated with protection against infection. Furthermore, RBD-NP when used in conjunction with AS03 was as potent as the prefusion stabilized Spike immunogen, HexaPro. Taken together, these data highlight the efficacy of the RBD-NP formulated with clinically relevant adjuvants in promoting robust immunity against SARS-CoV-2 in non-human primates.