Macrophages destroy bacteria by engulfing them in intracellular compartments, which they then acidify to kill or neutralize the bacteria.

Some pathogenic bacteria, such as Salmonella enterica, have evolved to exist and even grow within these acidified compartments. Yet, how Salmonella responds to the acidic environment and how that environment affects the virulence of this pathogen are unclear. New research reveals that Salmonella fights acid with acid, by lowering the pH of its own interior in response to the acidification of the Salmonella-containing compartment by the macrophage, and by using that low pH as a signal to turn on genes needed to establish an infection.

A newly discovered protein plays a central role in promoting immunity to viruses and cancer, according to experiments in mice and human cells.

 The hitherto unknown protein, which the researchers named lymphocyte expansion molecule, or LEM, modulates the proliferation of human T cells as well as in mice, by promoting the proliferation of cytotoxic T cells, which kill cancer cells and cells infected with viruses.

The discovery was unexpected because the new protein had no known function and doesn't resemble any other protein. Researchers from Imperial College London who led the study are now developing a gene therapy designed to boost the infection-fighting cells, and hope to begin human trials in three years. 
A new study demonstrates that macrophages can effectively substitute for so-called dendritic cells as primers of T-cell-dependent immune responses. They instead stimulate a broader-based response.

The immune response, the process by which the adaptive immune system reacts to, and eliminates foreign substances and cells, depends on a complex interplay between several different cell types. So-called dendritic cells, which recognize and internalize invasive pathogens, play a crucial role in this process.

A systematic review of the genomes of patients with ALK-negative anaplastic large cell lymphoma (ALCL), a particularly aggressive form of non-Hodgkin's lymphoma, shows that many cases of the disease are driven by alterations in the JAK/STAT3 cell signaling pathway. The study also demonstrates, in mice implanted with human-derived ALCL tumors, that the disease can be inhibited by compounds that target this pathway, raising hopes that more effective treatments might soon be developed. 

Human norovirus can cause an immune response in dogs so it leads to obvious concern over whether or not dogs can transmit it to other people.

Norovirus, which causes vomiting and diarrhea, is extremely contagious among humans. It infects 19-21 million Americans annually - more than six percent of the US population - according to the CDC. Those infections may result in as many as 71,000 hospitalizations, and 800 deaths.
Papain, found naturally in papaya and ioften referred to as a “plant-based pepsin”, is an important industrial protein-degrading enzyme for the food and cosmetic industries. The cosmetic industry uses papain in exfoliating treatments to remove dead surface skin and there even are enzyme-based shampoos for house pets to clean the fur and make it easier to brush. 

But lots of natural things can trigger allergic reactions. 

Genetic studies in humans, zebrafish and mice have revealed that two different types of genetic variations team up to cause a rare condition called Hirschsprung's disease, flaws in early nerve development that lead to poor colon function which must often be surgically corrected.

About one in every 5,000 babies is born with Hirschsprung's disease, which causes bowel obstruction and can be fatal if not treated. The disease arises early in development when nerves that should control the colon fail to grow properly. Those nerves are part of the enteric nervous system, which is separate from the central nervous system that enables our brains to sense the world.

A new paper provides evidence of a new mastrevirus, tentatively named switchgrass mosaic-associated virus 1 (SgMaV-1). Other members of the mastrevirus genus, a group of DNA viruses, are known to be responsible for decimating yields in staple food crops (including corn, wheat and sugarcane) throughout Africa, Europe, Asia and Australia.

It has never been reported in North America.

The switchgrass exhibited mosaic symptoms--splotchy, discolored leaves--characteristic of a viral infection, yet tested negative for known infections. Deep sequencing, a new technology, revealed the plants were infected with a new virus in the genus mastrevirus, the first of its kind found in North America.

Take this quick medical pop quiz: which of the following conditions would you prefer to have during your next stay in hospital? A. Staphylococcus aureus (golden staph) bloodstream infection; or B. a heart attack?

I am guessing most non-medical readers voted for the Staph option and, if my experience is anything to go by, the majority of medical readers will have also made a microbial choice.

Middle East Respiratory Syndrome (MERS), which emerged in humans last year in the Saudi Arabian peninsula, causes severe respiratory disease, with a mortality rate of 35 percent. No specific therapy is currently available. 

Passive immunization, a procedure where you inject a former patient's antibodies into a new patient to fight the disease, has been used in the past, including last year in a small number of cases of Ebola, but in the case of MERS, few former patients are available to donate antibodies. Additionally, their antibody titers are often too low, and many former patients are not healthy enough to donate.