Zoonotic diseases like COVID-19 and mpox (formerly monkeypox) have had a profound impact on global public health. Although these two diseases are caused by viral pathogens and share some similarities, their unique biological characteristics, transmission patterns, and public health implications require a differentiated approach. This article provides an in-depth analysis of mpox and COVID-19 to highlight their distinctions and the critical role of research in controlling these diseases.
Mpox and COVID-19 Causative Agents
The Long History of Mpox
Mpox is caused by the monkeypox virus (MPXV), a double-stranded DNA virus belonging to the Poxviridae family. First identified in 1958 in laboratory monkeys, MPXV was recognized in humans in 1970 in the Democratic Republic of the Congo (DRC). Unlike SARS-CoV-2, MPXV is not new and remains endemic to Central and Western Africa, where it primarily circulates among rodent species such as rope squirrels and Gambian pouch rats.
SARS-CoV-2 as a Novel Pathogen
SARS-CoV-2, the causative agent of COVID-19, is a single-stranded RNA virus from the Coronaviridae family. It was first identified in Wuhan, China, in late 2019. Unlike MPXV, SARS-CoV-2 emerged as a novel pathogen with no pre-existing immunity in humans, leading to widespread global transmission and a public health crisis of unprecedented scale.
Fig.1 MPox and COVID-19 Comparison Data
Structure of Mpox Virus and SARS-CoV-2
Structure of Mpox Virus
The mpox virus, in contrast, is much larger and structurally complex:
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Genome: MPXV's double-stranded DNA genome is approximately 197 kilobases long, encoding numerous proteins for replication, immune evasion, and host interaction.
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Size and Shape: MPXV is brick-shaped, with dimensions between 220-450 nm, making it one of the largest human-infecting viruses.
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Surface Proteins: The virus employs 11-12 transmembrane proteins to bind host molecules such as glycosaminoglycans, facilitating membrane fusion.
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Core Structure: MPXV's genome resides in a core structure containing enzymes needed for replication, allowing it to replicate within the cytoplasm without requiring access to the host nucleus.
Structure of SARS-CoV-2
SARS-CoV-2 is a small and streamlined virus optimized for rapid replication and host infection:
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Genome: The virus contains a single-stranded RNA genome about 30 kilobases in length, encoding structural, non-structural, and accessory proteins critical for its life cycle.
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Size and Shape: It is spherical with a diameter of ~100 nm.
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Spike Protein: The hallmark feature is the spike protein, which binds to ACE2 receptors on host cells, facilitating viral entry. This interaction is enhanced by host proteases like TMPRSS2.
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Lipid Envelope: Encasing the RNA genome is a lipid bilayer that helps evade immune defenses and stabilize the virus.
Evolutionary Differences Between SARS-CoV-2 and Mpox Virus
Evolution of Mpox Virus
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DNA Genome Stability: MPXV's DNA polymerase includes robust proofreading mechanisms, resulting in a slow mutation rate of approximately 1-2 mutations per year.
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Clade Classification: MPXV is divided into two major clades: clade I (more virulent, prevalent in Central Africa) and clade II (less virulent, prevalent in West Africa).
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Recent Mutations: Despite its slow evolution, the 2022 outbreak strain accumulated nearly 50 mutations compared to earlier strains, likely due to sustained human-to-human transmission.
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Implications: The slower mutation rate makes MPXV more stable for vaccine and diagnostic development, but unusual mutations warrant continued monitoring.
Evolution of SARS-CoV-2
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High Mutation Rate: As an RNA virus, SARS-CoV-2 uses RNA-dependent RNA polymerase (RdRp) for replication. While coronaviruses possess an exoribonuclease that offers limited proofreading, their mutation rate remains high.
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Emergence of Variants: The virus has evolved rapidly, producing numerous variants like Delta and Omicron, which differ in transmissibility, immune evasion, and pathogenicity.
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Public Health Impact: The rapid emergence of new variants has necessitated continuous vaccine updates and heightened surveillance.
How Mpox and COVID-19 Are Transmitted
Mpox transmission is predominantly through close, prolonged contact. Key transmission routes include:
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Skin-to-skin contact, including sexual contact.
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Respiratory droplets during prolonged face-to-face interactions.
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Contact with contaminated materials such as bedding or clothing.
COVID-19 Transmission
COVID-19 spreads much more easily through respiratory aerosols that can linger in the air, allowing for rapid transmission even from asymptomatic individuals. This airborne nature makes SARS-CoV-2 significantly more contagious than MPXV.
Symptoms of Mpox and COVID-19
Mpox symptoms usually appear 5-21 days after exposure and include:
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Fever, headache, swollen lymph nodes, and chills.
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A characteristic rash that progresses to pustules and scabs, often appearing on the face, extremities, and genitals.
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Most cases resolve within 2-4 weeks, though severe disease can occur, particularly in immunocompromised individuals.
COVID-19 Symptoms
COVID-19 symptoms range from mild to severe and typically include:
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Fever, cough, shortness of breath, and loss of taste or smell.
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Severe cases may progress to acute respiratory distress syndrome (ARDS).
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Some individuals develop Long COVID, characterized by persistent symptoms lasting months.
Diagnosis of Mpox and COVID-19
Mpox Testing Methods
Mpox diagnosis primarily relies on PCR testing, which is performed on lesion samples, such as fluid from pustules or dry scabs. This method provides high specificity and sensitivity, allowing accurate detection of the MPXV. However, testing is currently limited to specialized laboratories equipped with the necessary biosafety protocols, and there are no at-home or point-of-care diagnostic options available, posing challenges in accessibility. To aid research, Creative Biolabs provides MPXV detection services and MPXV detection kits, supporting virus studies.
COVID-19 Testing Methods
COVID-19 diagnostics include rapid antigen tests and PCR assays. Rapid tests, suitable for at-home use, deliver quick results, enabling early detection and isolation. PCR remains the gold standard for high-accuracy SARS-CoV-2 detection. The widespread availability of these tests has been pivotal in managing the pandemic, allowing timely diagnosis and containment of outbreaks.
Prevention of Mpox and COVID-19
Vaccination Strategies
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Mpox: The JYNNEOS vaccine, initially developed for smallpox, provides protection against mpox. Vaccination efforts focus on high-risk populations and close contacts.
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COVID-19: Multiple vaccines, including mRNA-based options like Pfizer-BioNTech and Moderna, have been developed to prevent severe disease and hospitalization.
Behavioral and Public Health Interventions
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Mpox: Avoiding close contact with infected individuals and contaminated materials, alongside proper hygiene, is key to controlling mpox outbreaks.
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COVID-19: In addition to hygiene measures, mask-wearing and social distancing are critical due to the virus's airborne transmission.
Public Health Impact of Mpox and COVID-19
Challenges in Mpox Response
Despite the availability of vaccines, mpox remains underreported in resource-limited settings. Companies like Creative Biolabs contribute to global efforts by developing advanced diagnostic kits and research tools, enabling better management of mpox and other zoonotic diseases.
Lessons Learned from COVID-19
The COVID-19 pandemic highlighted the need for global collaboration in vaccine development, diagnostics, and equitable distribution. These lessons are being applied to mpox outbreaks to improve containment efforts, especially in endemic regions.
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