Drivers and regulators of humoral innate immune responses to infection and cancer.

The complement cascade consists of cell bound and serum proteins acting together to protect the host from pathogens, remove cancerous cells and effectively links innate and adaptive immune responses. Despite its usefulness in microbial neutralization and clearance of cancerous cells, excessive complement activation causes an immune imbalance and tissue damage in the host. Hence, a series of complement regulatory proteins present at a higher concentration in blood plasma and on cell surfaces tightly regulate the cascade. The complement cascade can be initiated by B-1 B cell production of natural antibodies. Natural antibodies arise spontaneously without any known exogenous antigenic or microbial stimulus and protect against invading pathogens, clear apoptotic cells, provide tissue homeostasis, and modulate adaptive immune functions. Natural IgM antibodies recognize microbial and cancer antigens and serve as an activator of complement mediated lysis. This review will discuss advances in complement activation and regulation in bacterial and viral infections, and cancer. We will also explore the crosstalk of natural antibodies with bacterial populations and cancer.

Rift Valley Fever Viral RNA Detection by In Situ Hybridization in Formalin-Fixed, Paraffin-Embedded Tissues.

Sporadic outbreaks of Rift Valley fever virus (RVFV), a zoonotic, mosquito-borne Phlebovirus, cause abortion storms and death in sheep and cattle resulting in catastrophic economic impacts in endemic regions of Africa. More recently, with changes in competent vector distribution, growing international trade, and its potential use for bioterrorism, RVFV has become a transboundary animal disease of significant concern. New and sensitive techniques that determine RVFV presence, while lessening the potential for environmental contamination and human risk, through the use of inactivated, noninfectious samples such as formalin-fixed, paraffin-embedded (FFPE) tissues are needed. FFPE tissue in situ hybridization (ISH) enables the detection of nucleic acid sequences within the visual context of cellular and tissue morphology. Here, we present a chromogenic pan-RVFV ISH assay based on RNAscope® technology, which is able to detect multiple RVFV strains in FFPE tissues, enabling visual correlation of RVFV RNA presence with histopathologic lesions.