key: cord-0781038-a8198zc4 authors: Gilliland, Theron; Liu, Yanan; Li, Rong; Dunn, Matthew; Cottle, Emily; Terada, Yutaka; Ryckman, Zachary; Alcorn, Maria; Vasilatos, Shauna; Lundy, Jeneveve; Larson, Deanna; Wu, Hua; Luke, Thomas; Bausch, Christoph; Egland, Kristi; Sullivan, Eddie; Wang, Zhongde; Klimstra, William B. title: Protection of human ACE2 transgenic Syrian hamsters from SARS CoV-2 variants by human polyclonal IgG from hyper-immunized transchromosomic bovines date: 2021-07-26 journal: bioRxiv DOI: 10.1101/2021.07.26.453840 sha: ec0adb1932671359f37ec98cffc71da1184bfcb5 doc_id: 781038 cord_uid: a8198zc4 Pandemic SARS CoV-2 has been undergoing rapid evolution during spread throughout the world resulting in the emergence of many Spike protein variants, some of which appear to either evade antibody neutralization, transmit more efficiently, or potentially exhibit increased virulence. This raises significant concerns regarding the long-term efficacy of protection elicited after primary infection and/or from vaccines derived from single virus Spike (S) genotypes, as well as the efficacy of anti-S monoclonal antibody based therapeutics. Here, we used fully human polyclonal human IgG (SAB-185), derived from hyperimmunization of transchromosomic bovines with DNA plasmids encoding the SARS-CoV-2 Wa-1 strain S protein or purified ectodomain of S protein, to examine the neutralizing capacity of SAB-185 in vitro and the protective efficacy of passive SAB-185 antibody (Ab) transfer in vivo. The Ab preparation was tested for neutralization against five variant SARS-CoV-2 strains: Munich (Spike D614G), UK (B.1.1.7), Brazil (P.1) and SA (B.1.3.5) variants, and a variant isolated from a chronically infected immunocompromised patient (Spike Δ144-146). For the in vivo studies, we used a new human ACE2 (hACE2) transgenic Syrian hamster model that exhibits lethality after SARS-Cov-2 challenge and the Munich, UK, SA and Δ144-146 variants. SAB-185 neutralized each of the SARS-CoV-2 strains equivalently on Vero E6 cells, however, a control convalescent human serum sample was less effective at neutralizing the SA variant. In the hamster model, prophylactic SAB-185 treatment protected the hamsters from fatal disease and minimized clinical signs of infection. These results suggest that SAB-185 may be an effective treatment for patients infected with SARS CoV-2 variants. SARS CoV-2 has spread worldwide during the previous year resulting in over 140 million cases and over 3 million deaths (WHO dashboard https://covid19.who.int) 1 . In late fall 2020, variant viruses were identified that exhibited altered infection, transmission and disease characteristics 2 reviewed in 3-6 . These variants may reflect immune response escape mutants as well as mutants adapting to replication and transmission in normal or immunocompromised human populations 7 8,9 , reviewed in 10, 11 . Of particular concern are variants with multiple changes in the Spike protein that is a primary target of acquired immune responses, since these viruses could exhibit increased resistance to Spiketargeted vaccines and immuno-therapeutics 7,8,12,13 reviewed in [14] [15] [16] [17] . Genetically modified transchromosomic bovines (Tc-bovines) adaptively produce fully human polyclonal antibodies after exposure to environmental or vaccine antigens [18] [19] [20] . After hyperimmunization, Tc-bovines produce high titer, fully human IgG (Tc-hIgG) that can be rapidly produced from their plasma [21] [22] [23] Production and purification of the SAB-185 human IgG preparation has been described 24 . Briefly, transchromosomic bovines were hyperimmunized two times with a DNA plasmid expressing the WA-1 S protein followed by three times with recombinant spike ectodomain produced and purified from insect cells. Plasma was collected on 8, 11 Figure 2A ). Times to death were not significantly different between the SARS CoV-2 variants Weight loss was measured daily for all animals after challenge ( Figure 3 ). Combined control group average weights began decreasing between D1 and D2 post challenge and were significantly different from SAB-185 treated groups animals on D4, 5 and 6 ( Figure 3B ). On D5, the last day on which all but one control animal were alive, Munich, and SA challenge groups were exhibited significantly lower weight loss than controls but the UK and D144-146 challenged animals did not ( Figure 3E , G, I, K). All but one surviving mock-treated male animal lost weight over the course of the experiment suggesting that infection of that animal may have been very limited ( Figure 3J ). Only one SAB-185 treated animal (D144-146 group, Figure Oropharyngeal swab plaque titers for all hamsters were below the limit of detection of a plaque assay (25 PFU/ml) on D1, 3, 5, 7 and 11 post challenge suggesting that genomic RNA detected by the PCR assay was not associated with high levels of live virus. The current pandemic has yielded significant surprises for the scientific community Results were evaluated for statistical significance with GraphPad PRISM software. Mortality curves were evaluated using Mantel-Cox Log-Rank analysis. Average weight loss, clinical sign and virus titration data were compared with two-way ANOVA. Individual time points in particular assays were compared between two treatments with a two-tailed Student's t test. 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