Human coronavirus NL63

Human coronavirus NL63 (HCoV-NL63), first identified in late 2004, is a species of coronavirus that infects humans and possibly other primates. It is associated with a range of respiratory symptoms, from the common cold to more severe conditions such as bronchiolitis and pneumonia. HCoV-NL63 is of particular interest in the medical community due to its unique entry mechanism into human cells and its potential implications for understanding and treating other coronavirus infections.

Discovery

HCoV-NL63 was first isolated in the Netherlands by a team of virologists in 2004 from a 7-month-old child suffering from bronchiolitis and conjunctivitis. The discovery was significant as it added to the growing list of coronaviruses capable of infecting humans, including the previously identified HCoV-229E, HCoV-OC43, and the severe acute respiratory syndrome coronavirus (SARS-CoV).

Transmission

The virus is primarily spread through respiratory droplets produced when an infected person coughs or sneezes. It can also be transmitted by close personal contact, such as touching or shaking hands, and then touching the mouth, nose, or eyes before washing hands. There is evidence to suggest that HCoV-NL63 can be spread through fomites—objects or materials which are likely to carry infection.

Symptoms

Infection with HCoV-NL63 can lead to a wide range of symptoms, from none at all to severe respiratory illness. Common symptoms include fever, runny nose, cough, and sore throat. In infants and young children, it can cause croup, an infection of the upper airway, which obstructs breathing and leads to a characteristic barking cough.

Pathogenesis

HCoV-NL63 uses the angiotensin-converting enzyme 2 (ACE2) receptor to enter human cells, similar to the mechanism employed by the SARS-CoV. This discovery has spurred research into the role of ACE2 in coronavirus infections and the potential for targeting this receptor in treatments.

Diagnosis

Diagnosis of HCoV-NL63 infection is typically performed using reverse transcription polymerase chain reaction (RT-PCR) from a nasopharyngeal swab. Serological tests to detect antibodies against HCoV-NL63 can also be used to identify past infections.

Treatment and Prevention

There is no specific antiviral treatment recommended for HCoV-NL63 infection. Management involves supportive care, including rest, fluids, and over-the-counter fever reducers and pain relievers. Prevention strategies are similar to those for other respiratory infections and include frequent handwashing, avoiding close contact with sick individuals, and practicing good respiratory hygiene.

Epidemiology

HCoV-NL63 is found worldwide and infects people of all ages. It is more prevalent in children and immunocompromised individuals. The virus has a seasonal pattern in temperate climates, with infections peaking in winter and early spring.

Research

Research on HCoV-NL63 continues to focus on understanding its biology, epidemiology, and clinical implications. Studies on the virus's interaction with the ACE2 receptor are particularly relevant for the development of therapeutic strategies not only for HCoV-NL63 but also for other more severe coronaviruses like SARS-CoV and SARS-CoV-2.