Novel Herpesvirus Discovered in South American Sea Lions, Study Shows

Sea lions are among the most charismatic and beloved animals in the world. They are often seen as playful, intelligent, and social creatures that delight tourists and locals alike.

But behind their charming appearance, there is a hidden danger that could jeopardize their future: a novel herpesvirus that has been detected in their populations.

A Novel Herpesvirus Emerges

A recent study published in PLOS ONE has revealed the presence of two new types of herpesviruses in free-ranging South American sea lions (Otaria byronia).

These viruses, named Otariid gammaherpesvirus 1 (OtGHV1) and Otariid gammaherpesvirus 8 (OtGHV8), belong to a group of pathogens that can cause various diseases in animals and humans, such as cancer, respiratory infections, and skin lesions.

The study, which involved researchers from several institutions, including Brookfield Zoo Chicago, Programa Punta San Juan, Shedd Aquarium, and University of Illinois Wildlife Epidemiology Lab, is the first to report these viruses in South American pinnipeds.

The researchers collected samples from 172 sea lions from Peru and Argentina and tested them for herpesvirus DNA using a technique called polymerase chain reaction (PCR). They found that 42% of the samples were positive for OtGHV1 and 26% were positive for OtGHV8.

The discovery of these viruses is remarkable because it expands the diversity and distribution of herpesviruses among pinnipeds, which are aquatic mammals that include seals, sea lions, and walruses.

Previous studies have identified other types of herpesviruses in pinnipeds from different regions, such as North America, Europe, and Antarctica, but this is the first time that these viruses have been detected in South America.

The researchers suspect that these viruses may have originated from other pinniped species that share the same habitat or have overlapping geographic ranges with the South American sea lions.

For example, OtGHV1 is well documented in California sea lions (Zalophus californianus) in the Northern Hemisphere and is associated with high rates of urogenital (bladder, kidney, prostate, and other urinary tract) cancer.

However, northern fur seals (Callorhinus ursinus), which also inhabit the Pacific coast of North America, have not shown any evidence of OtGHV1 infection or cancer despite large-scale surveillance.

This suggests that California sea lions may have acquired OtGHV1 from another source, such as a different pinniped species or a terrestrial animal.

Similarly, OtGHV8 is a novel virus that has not been reported in any other pinniped species so far. The researchers hypothesize that it may have emerged from a recombination event between two existing herpesviruses, such as OtGHV1 and another gammaherpesvirus.

Recombination is a process in which two or more viral genomes exchange genetic material, resulting in a new virus with different characteristics.

This phenomenon has been observed in other herpesviruses, such as human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV), which can cause various diseases in humans.

The Potential Impact on Sea Lion Health and Conservation

The implications of this finding are not yet clear, but they could be significant for the health and conservation of South American sea lions and their ecosystems.

Herpesviruses are known to be opportunistic pathogens, which means that they can take advantage of weakened immune systems or stressful conditions to cause disease.

Some of the factors that could trigger herpesvirus infections in sea lions are environmental changes, human disturbances, pollution, and competition for food and space.

The researchers suggest that further studies are needed to determine the prevalence, transmission, and pathogenicity of these viruses in sea lions and other pinnipeds.

They also recommend monitoring the health status and population trends of these animals, as well as implementing preventive measures to reduce the risk of exposure and infection.

Sea lions are important components of marine ecosystems, as they play a role in regulating prey populations, maintaining biodiversity, and providing food and services for humans.

They are also vulnerable to various threats, such as overfishing, habitat loss, climate change, and disease outbreaks. Therefore, understanding and protecting their health is essential for their survival and well-being.