SARS-CoV-2 Variant Spike and accessory gene mutations alter pathogenesis.

The ongoing COVID-19 pandemic is a major public health crisis. Despite the development and deployment of vaccines against SARS-CoV-2, the pandemic persists. The continued spread of the virus is largely driven by the emergence of viral variants, which can evade the current vaccines through mutations in the Spike protein. Although these differences in Spike are important in terms of transmission and vaccine responses, these variants possess mutations in the other parts of their genome which may affect pathogenesis. Of particular interest to us are the mutations present in the accessory genes, which have been shown to contribute to pathogenesis in the host through innate immune signaling, among other effects on host machinery. To examine the effects of accessory protein mutations and other non-spike mutations on SARS-CoV-2 pathogenesis, we synthesized viruses where the WA1 Spike is replaced by each variant spike genes in a SARS-CoV-2/WA-1 infectious clone. We then characterized the in vitro and in vivo replication of these viruses and compared them to the full variant viruses. Our work has revealed that non-spike mutations in variants can contribute to replication of SARS-CoV-2 and pathogenesis in the host and can lead to attenuating phenotypes in circulating variants of concern. This work suggests that while Spike mutations may enhance receptor binding and entry into cells, mutations in accessory proteins may lead to less clinical disease, extended time toward knowing an infection exists in a person and thus increased time for transmission to occur. Significance: A hallmark of the COVID19 pandemic has been the emergence of SARS-CoV-2 variants that have increased transmission and immune evasion. Each variant has a set of mutations that can be tracked by sequencing but little is known about their affect on pathogenesis. In this work we first identify accessory genes that are responsible for pathogenesis in vivo as well as identify the role of variant spike genes on replication and disease in mice. Isolating the role of Spike mutations in variants identifies the non-Spike mutations as key drivers of disease for each variant leading to the hypothesis that viral fitness depends on balancing increased Spike binding and immuno-evasion with attenuating phenotypes in other genes in the SARS-CoV-2 genome.

Immunocytochemical localization of follicle stimulating hormone in normal human stomach.

Immunoreactive follicle-stimulating hormone (IR-FSH) is detected in sections of formalin-fixed and paraffin-embedded gastric mucosal tissue of normal men, using the immunoperoxidase staining technique and specific antisera to hFSH (NIDDK, NIH). Positive staining for IR-FSH was detected in the parietal cells lining the gastric glands of the intermediate zone. The staining was intracytoplasmic and distributed throughout the cytoplasm. IR-FSH was also found to be present in the basal part of the foveolar epithelium. Stromal tissue and nuclei were devoid of the stain. The zymogen cells in the deeper region of the mucosa did not show any detectable staining for IR-FSH. The presence of IR-FSH in gastric mucosa was also detected by radioimmunoassay. Gel chromatography of the gastric tissue extract showed a single peak of FSH immunoreactivity that coeluted with the 125I-labeled highly purified FSH preparation (NIDDK, NIH). Furthermore, the FSH in the pituitary tissue extract had a chromatographic profile similar to that of IR-FSH from gastric tissue, and 125I-FSH labeled highly purified FSH, indicating a close resemblance in their molecular sizes. These results demonstrate that IR-FSH is present in the normal human gastric mucosa. The role of this regulatory petpide in gastric tissue, if any, needs to be investigated.

Immunoreactive-FSH in human normal gastric mucosa.

Using indirect immuno-peroxidase staining technique, localization of immunoreactive follicle-stimulating hormone (IR-FSH) is demonstrated in the cytoplasm of the epithelial cells of normal human stomach. In view of their triangular shape and central nucleus and their predominance in the intermediate glands of the gastric mucosa, these cells are identified as parietal cells. The stromal tissue is devoid of staining reaction.

Biosynthesis and localization of inhibin in human prostate.

Inhibin biosynthesis by human prostatic tissue was investigated in vitro. Serum levels of inhibin as well as tissue concentrations in different cells and zones of the normal and benign hyperplastic prostates were determined. Immunocytochemical localization of inhibin identified the involvement of epithelial but not stromal cells in the synthesis and release of prostatic inhibin into the circulation. The endocrine and paracrine functions of prostatic inhibin remain to be elucidated.