SARS-CoV-2, the causative agent of COVID-19, emerged in late 2019 and rapidly spread globally, leading to unprecedented public health measures and research efforts. The virus causes a wide range of symptoms from asymptomatic infection to severe respiratory disease and multi-organ complications. Rapid vaccine development and therapeutic advances have transformed the pandemic response, though viral evolution continues to present ongoing challenges for long-term disease control. 

Several variants available.

Human coronaviruses (NL63, 229E, OC43) are well adapted to humans, circulating widely and mostly causing only mild disease in immunocompetent adults. These CoVs can be incredibly useful research tools and surrogates for the BL3 coronaviruses (e.g., SARS-CoV-2).

Although generally harmless in adults, RSV remains the main cause of viral-induced pneumonia in infants and young children globally. Recent years have seen the approval of new RSV vaccines and preventive treatments after decades of research. The virus continues to be a priority target for antiviral development and respiratory disease research.

RSV A and B strains available.

HMPV is a leading cause of acute respiratory tract infections in children, the elderly, and immunocompromised individuals. Discovered relatively recently in 2001, the virus causes symptoms ranging from mild cold-like illness to severe bronchiolitis and pneumonia. HMPV is now recognized as the second most common cause of viral respiratory illness in young children after RSV.

Currently, there are no licensed vaccines or specific antiviral treatments for HMPV. The virus presents unique challenges for vaccine development due to concerns about vaccine-enhanced disease, similar to those encountered with RSV. Research efforts focus on understanding viral pathogenesis and developing safe, effective interventions for this important respiratory pathogen.

Rhinoviruses are the most common cause of upper respiratory tract infections, responsible for approximately 50% of common colds and causing billions of dollars in economic losses annually through missed work and school days. With over 160 distinct serotypes, the virus presents significant challenges for vaccine development and has largely evaded attempts at universal prevention strategies. Despite causing generally mild symptoms, rhinoviruses can trigger serious complications in individuals with asthma or chronic obstructive pulmonary disease, making them an important target for therapeutic research.

hought to be diffused across several European countries, frequent outbreaks of Sindbis virus infections have been reported in Finland and Sweden. Diseases can be mild or asymptomatic, but in a considerable number of cases SINV infection leads to persistent joint manifestations that can continue for months or years or even become chronic.

Besides being a human pathogen, Sindbis virus is also studied as a model alphavirus and to understand the molecular and immune bases of virus-induced arthritogenic diseases.

Semliki Forest virus rarely causes disease in humans. However, it has been widely adopted as a research tool because of its efficient replication and broad host range. Simliki has been used in the development of gene therapy and as a vector for vaccines and anti-cancer agents. Its neurotropism makes it also a vector of choice for gene delivery to neurons.

Despite the introduction of a highly effective vaccine, yellow fever virus still causes recurrent and deadly outbreaks in Africa. The vaccine strain 17D has been attenuated via several passages of the virulent Asibi strain in chicken embryo tissues, in order to reduce its viscero- and neuro-tropism. The safe vaccine strain YF17D is routinely used to study the biology of yellow fever virus and to understand the immunologic properties of one of the best vaccines ever developed.

Zika virus infection is mostly asymptomatic or can result in a mild illness. However, the 2013 epidemic of Zika in the Americas has caused alarm due to the now-established link between Zika infection and microcephaly (reduced head size and brain damage) in newborn babies. Although major efforts are being directed towards a Zika vaccine, many unique aspects of Zika virus infection remain elusive, including the link between viral infection and pathogenesis, and what caused such a rapid diffusion of the Asian strains.

African and Asian strains are available.

HSV-1 is one of the most prevalent human pathogens globally, primarily causing oral herpes and cold sores, though it can also lead to genital herpes and severe encephalitis. The virus establishes lifelong latency in nerve cells with periodic reactivation throughout the infected person’s lifetime. Despite extensive research, no preventive vaccine exists, making HSV-1 an important target for therapeutic development and a valuable model for studying viral latency mechanisms.

HSV-2 primarily causes genital herpes and affects approximately 491 million people worldwide, significantly increasing the risk of HIV acquisition and transmission. Like HSV-1, the virus establishes persistent latent infection in nerve cells with periodic symptomatic reactivation. Recent vaccine trials have shown limited efficacy, highlighting the continued need for novel preventive and therapeutic approaches against this challenging pathogen.

Vaccinia virus is the poxvirus that was used to eradicate Variola virus, or smallpox, a much more aggressive and highly lethal member of the same family. Vaccinia is a large DNA virus that is still used to date as a model poxvirus, and as a vector to design safer and more immunogenic vaccines. Also, its complex network of interaction with cellular proteins makes vaccinia an invaluable tool to discover new cellular functions and defense mechanisms.

Despite the availability of a highly effective vaccine, measles remains a significant global health concern, causing over 200,000 deaths annually. The virus is one of the most contagious pathogens known, with the potential to cause severe complications, including pneumonia, encephalitis, and immune suppression that can persist for years after infection.

Recent outbreaks in developed countries underscore the importance of maintaining high vaccination coverage. Research continues into the measles virus as an oncolytic therapy platform and into understanding the mechanisms behind measles-induced immune amnesia, which leaves survivors vulnerable to other infections.

Murine norovirus serves as the primary research model for human noroviruses, which are the leading cause of viral gastroenteritis worldwide but remain difficult to culture in laboratory settings. The virus is naturally found in laboratory mouse colonies and provides crucial insights into norovirus biology, immune responses, and antiviral development. Murine norovirus research has been instrumental in understanding norovirus persistence, transmission mechanisms, and evaluating the efficacy of disinfectants and potential therapeutic interventions.

Adenoviruses are common human pathogens causing respiratory, gastrointestinal, and ocular infections, with over 50 serotypes identified that can affect different organ systems. Beyond their role as natural pathogens, adenoviruses have become invaluable research tools and are widely used as vectors for gene therapy, vaccine delivery, and oncolytic cancer treatments. The virus’s ability to infect both dividing and non-dividing cells, combined with well-characterized biology and ease of genetic manipulation, makes it a cornerstone of modern virology research and therapeutic development.

Coxsackieviruses are enteroviruses divided into Group A (causing hand, foot, and mouth disease and herpangina) and Group B (associated with more severe conditions including myocarditis, meningitis, and pancreatitis). These viruses primarily affect children and are highly contagious, spreading through respiratory droplets and fecal-oral transmission. With no specific antiviral treatments or vaccines available for most serotypes, coxsackieviruses remain important targets for therapeutic research and serve as key models for understanding enterovirus pathogenesis.

Enterovirus D68 primarily causes respiratory illness in children and gained significant attention following large outbreaks that resulted in severe breathing difficulties requiring intensive care. The virus has been associated with acute flaccid myelitis, a rare but serious polio-like paralytic condition that predominantly affects children. With no specific antiviral treatments or vaccines available, EV-D68 remains a priority for public health surveillance and therapeutic research, particularly given its potential for causing severe neurological complications.