Monkeypox is a double-stranded DNA virus while SARS-CoV-2 is a single-stranded RNA virus. The two viruses share some similarities—both are enveloped, both replicate in the cytoplasm, and both need a host (either human or animal) and cellular machinery to replicate and manufacture more viral proteins. Both viruses have also caused substantial concern about engaging in the social interactions so important to forming and sustaining close relationships. Understanding how viruses work, and how our bodies have adapted to handle infections, is one way to be reasonably informed and vigilant while remaining active and engaged in the joys of life.
At the moment, monkeypox cases are being detected predominantly among gay and bisexual men but the virus is not a gay virus. Monkeypox is an infectious disease and its transmission is not constrained to a specific social network. Covid is now recognized to be a virus that will be universally infectious—it is not a disease of the unvaccinated.
While the news cycle is focusing on monkeypox, other sexually transmitted infections have been detected in approximately one-third of monkeypox cases, underscoring the variety of viruses in circulation as society reopens. It is likely only a matter of time before the epidemiology of monkeypox becomes more diverse as community spread continues.
While monkeypox vaccine supplies are limited, health officials are making a conscious effort to improve messaging and access to testing and treatment. The steep rise in monkeypox cases has caused concern about stigmatization surrounding seeking testing and care, but CDC messaging has been direct, accessible and frequent. Similar to the early months of the Covid response, local health departments are again facing resource constraints but are making every effort to ensure those most at risk of monkeypox infection have rapid access to protection through testing and vaccination.
Differences in community transmission
Monkeypox is primarily passed from person to person by very close physical contact whereas COVID-19 illness is caused by airborne transmission of the virus SARS-CoV-2. Once infected with either virus, people may develop mild to severe illness, or even no symptoms at all. Both viruses can be transmitted to a pet by close contact or food sharing.
Although monkeypox is much harder to catch than SARS-CoV-2, scientists are still researching whether the virus can be transmitted by a person without symptoms, via seminal fluid, and what the risk factors are for more serious illness. This process takes time, but the intense focus on SARS-CoV-2 has prepared the scientific community with the tools and methods to research these questions more quickly.
By exploring the differences and similarities between these two viruses, we gain insight into the clever tactics used by viruses to enter human cells and cause infection. Any sudden uptick in new infections is cause for further investigation, but our immune system has evolved over millennia along with the viruses in our environment, allowing us to build new defenses as the viruses mutate.
Similar tactics for cell entry
Once two humans come in close contact, the enveloped viruses like monkeypox and SARS-CoV-2 can enter the host cell through a process called endocytosis. The process is complex and the specific tactics employed vary from virus to virus, but the goal is the same: trick the cell into allowing the virus to be easily absorbed. The virus borrows (steals might be more appropriate) lipids and proteins from the host’s own cell membranes to create the “envelope.” This “Trojan horse” tactic allows the virus to hide in a disguised capsule which can fuse with the host cell membrane. With endocytosis accomplished, viral DNA or RNA is released into the cytoplasm before it is detected as foreign material. The virus then uses cellular machinery to manufacture more viral proteins which are displayed on the cell surface and used to continue the cycle of infection. These proteins are the antigens which trigger antibody production.
When roving immune cells looking for “non-self” invaders notice the antigens, a cascade of immune signals induces antibody production and other first-responders tell the infected cells to self-destruct. For people who have been previously vaccinated or recovered from infection, antibodies are already on standby waiting to bind to the antigens and block infection. This is why infection does not always proceed to disease, and why vaccination is so effective.
If the immune system is unable to contain this viral replication after infection, disease can develop. This distinction between infection and disease is important. Infection is the process of gaining entry to a cell, whereas disease is the manifestation of symptoms in response to an infection. Vaccines generally prevent disease, not infection.
How to kill enveloped viruses
The poxviruses tend to be more stable in the environment than other enveloped viruses, but both SARS-CoV-2 and monkeypox are considered tier 1 emerging viral pathogens by the Environmental Protection Agency (EPA) and can be killed by common disinfectants. Perhaps reassuringly, Tier 1 viruses are easier to kill than Tiers 2 or 3, and generally speaking, high heat and humidity can inactivate viruses.
Monkeypox typically uses animals as hosts, but it can jump from animals to humans. In fact, an outbreak in 2003 in the US was linked to keeping prairie dogs as pets. The human cases had handled sick pets or touched the bedding of the pets. When viruses jump from animals to humans and back again, they collect adaptations. This is how variants can arise which may carry new mechanisms for cell entry. For example, the Omicron variant was able to evade antibodies to the original spike protein and tended to use endocytosis instead of relying on the spike protein to “unlock” a port of entry.
Humans need fitness, too
Viruses adapt over time to improve their “fitness” for propagation. We can also improve our fitness to withstand constant exposure to pathogens. Various factors can influence immune health, such as age, immunocompromising conditions or medications, and overall health. It may sound trite, but sleep, exercise and hydration may be the most critical steps we can take to stay healthy. Try stacking 30 minutes of social media time with exercise to improve your wellbeing?