Junin Virus Vaccine Antibodies Can Also Fight Machupo Virus

In a recent study, researchers have found that a vaccine for Junin virus effectively induced antibodies for another hemorrhagic fever virus, raising the possibility for the development of a universal vaccine for such viruses.

There are at least 20 known viral hemorrhagic fevers worldwide, including Ebola, Lassa fever, and Rift Valley fever. According to the Centers for Disease Control and Prevention (CDC), these diseases are caused by viruses from 5 families — Arenaviridae, Bunyaviridae, Filoviridae, Flaviviridae, and Paramyxoviridae. Each hemorrhagic fever virus is geographically restricted to the habitats of the animals and insect hosts that serve as their natural reservoirs. While humans can become infected with these viruses, they are not the natural reservoirs, though in some cases the viruses can be passed from human to human. While hemorrhagic fever viruses can cause relatively mild illness, others can cause bleeding and severe illness in humans. Such severe cases can affect multiple organ systems, damage the overall vascular system, and impair the body’s ability to regulate itself.

Junin virus, the cause of Argentine hemorrhagic fever, is one of 5 arenaviruses that cause human hemorrhagic fevers. First discovered in 1958, the Argentine hemorrhagic fever virus occurs in a limited agricultural area of the pampas in Argentina and is spread to humans through the inhalation of excrement from infected rodent hosts or through contact on wounds or abrasions. Symptoms of the condition include high fever, malaise, chills, headache, nausea, and vomiting, with a case fatality rate of 15% to 30% without treatment. More than 1 million individuals live in areas where the disease is endemic, and a vaccine for Argentine hemorrhagic fever available since 1991 has brought a steady decline in the incidence of infections.

In a new study published in the journal Nature Communications, Harvard Medical School researchers have found that antibodies elicited with the Junin virus vaccine are also effective against Machupo virus, another arenavirus first isolated in Bolivia. The researchers isolated 2 antibodies from the blood of a Junin vaccine recipient and discovered that a small portion of the virus’ protein receptor binding site (RBS) needed to attach to a host cell was identical to that of Machupo virus. The findings support anecdotal observations that humans and primates vaccinated for Junin virus have more resilience against Machupo virus.

"Even among viruses that are related and share similarities in the molecular makeup of their receptor bindings sites, you still end up with a substantial degree of variability," explained senior author Jonathan Abraham, MD, PhD, in a recent statement. "Our findings raise the tantalizing possibility of designing universal therapies using antibodies made to one virus for which there is a vaccine as a way to prevent or treat other viruses for which there are none."

In an interview with Contagion^®, Dr. Abraham points out that the Ebola outbreak of 2014-2016 highlighted the importance of having effective vaccines available in real time to limit the size of outbreaks. The new findings, he says, could have implications beyond arenaviruses.

“I think they are a step in the right direction for understanding how to develop vaccines that would protect against closely related viruses as a better way to prepare ourselves against future outbreaks,” said Dr. Abraham.” Much more work is needed of course to figure out how this could be achieved for arenaviruses, and other agents that cause viral hemorrhagic fevers.”

Picture Source: CDC / Dr. Fred Murphy; Sylvia Whitfield . Picture Caption: Electron photomicrograph of the Machupo Virus. Machupo Virus is a member of the Arenavirus family, isolated in the Beni province of Bolivia in 1963; Viral hemorrhagic Fever.