viroLOGICAL

Lymphocytic choriomeningitis virus (LCMV) is an arenavirus closely related to Lassa virus, but unlike Junin virus it isn’t limited to South America: it’s found worldwide in house mice. Florian Krammer explains how people get infected, mostly by inhaling dust from dried mouse urine, droppings or saliva, and less often through bites, contaminated food or infected pets like hamsters.

Since the 1970s, cats in Sweden, and later in and around Vienna, have been falling ill with a mysterious brain inflammation known as staggering disease. Affected cats develop fever, behavioral changes, a staggering gait and often paralysis of the hind legs, and most have to be euthanized. For decades Borna disease virus was the main suspect, but metagenomics finally solved the case: in 2023, rustrela virus, a close relative of rubella virus, was detected in 27 out of 29 affected cats from Sweden, Germany and Austria.

Junin virus causes Argentine hemorrhagic fever, a disease with a case fatality rate of 20 to 30 percent. Florian Krammer explains why these New World arenaviruses are named after sand (they package host cell ribosomes that look like grains of sand under the electron microscope) and what makes their spike protein unusual: the signal peptide stays part of the glycoprotein complex, something found nowhere else in biology. The virus is carried by field mice, mainly the dryland vesper mouse, and people usually get infected by inhaling dust from dried urine and feces. That's why it mostly affects men working in...

Human metapneumovirus (HMPV) is one of the most common respiratory viruses there is, yet few people have heard of it. Florian Krammer explains why this relative of RSV is the second most common cause of respiratory illness in children under five and is behind 8 to 15 percent of pneumonia cases in that age group.