To understand how viruses reproduce, we need to look at two specific subjects:
WHAT IS A VIRUS?
A virus is a small infectious agent that can replicate (reproduce) only inside the living cells of an organism. Viruses can infect all types of organisms, from animals and plants to bacteria and all forms of living entities – but they CANNOT REPRODUCE BY THEMSELVES! Viruses require the ability to attach to and insert their virus DNA or RNA into a human host cell in order to reproduce.
Since the discovery in 1898 of the tobacco mosaic virus, about 5,000 viruses have been discovered and described in detail – although there are millions of different types. Viruses are by far the most single abundant biological entities on Earth – far outnumbering all other types of living organisms combined!
Viruses are found wherever there is life and have probably existed since living cells first evolved. Recent discoveries have uncovered that even parts of our human DNA contain remnants of ancient virus DNA!
Virus particles are also known as ‘virions’, and they are typically comprised of only a few components:
First, there is the virus' genetic material in the form or either DNA or RNA – long molecules that carry genetic information and the instructions for viral replication.
Next, there is a protein coating that protects these genes – a capsule, envelope, or ‘nucleocapsid’. In some cases there is an additional layer of lipids that surrounds the protein coat when the virus particles are outside a host cell.
In many viruses there is a ‘tegument’, also known as a ‘viral matrix’, lining the space between the nucleocapsid (the inner portion of the virus) and the virus' outer envelope, or virus membrane. The tegument is made of proteins which aid in virus DNA replication, as well as helping the virus evade the body’s immune system.
Most viruses have structures around the outside of the virus envelope that are used as attachment points – spike-like structures where the virus particle attaches itself to, and penetrates the membrane of its target host cell. This is becoming a more and more important element in the fight against viral disease.
THE VIRUS LIFE CYCLE
Viruses do not reproduce through cell division, because they are ‘acellular’. Instead, they use the components, mechanisms and metabolic processes of a host cell to produce multiple copies of themselves, and they assemble inside the host cell before the newly formed virus particles are released into the system, each one finding the next host cell to attach to, and repeating the reproduction cycle over and over.
The exact life cycle of viruses differs between species but science agrees that there are six basic stages in the life cycle of viruses:
STAGE 1: ATTACHMENT
‘Attachment’ is the first stage in the virus life cycle following introduction of the virus into the body. It refers to the binding (or attachment) between the proteins that line or surround the virus capsid and specific receptors on the cellular surface of the targeted host cell.
If attachment – also called ‘VIRUS FUSION’ – does not or cannot occur successfully, the virus life cycle is cut short, and the immune system can act to eliminate the attacking virus particle before it has had a chance to penetrate the host cell wall and insert its DNA or RNA.
STAGE 2: PENETRATION
Following successful attachment to a host cell, the next stage in the virus life cycle is called ‘Penetration’. Viruses enter the host cell through receptor-mediated ‘endocytosis’ (breaching the host cell wall) or membrane fusion. This is often called ‘virus entry’. Viruses penetrate their host cells through spike-like extensions on the outside envelope of the virus which can puncture the host cell membrane.
Penetration has one singular objective: to insert the virus' DNA or RNA inside the host cell, where it can start the process of replication, creating new virus particles. Remember that Penetration cannot occur until Attachment (or Virus Fusion) has been achieved.
STAGE 3: UNCOATING
Following successful Virus Fusion (or Virus Attachment) and having penetrated the host cell wall and inserting its virus DNA or RNA into the host cell, the next stage in the virus life cycle is called ‘Uncoating’.
Uncoating is a process in which the virus capsid is removed: This may be accomplished by degrading the virusenvelope with viral enzymes or host cell enzymes, or by simple dissociation of the virus capsule.
The end result, or objective, of Uncoating is the releasing of the virus' genomic nucleic acid (the virus’ DNA or RNA), which starts the process of virus replication and reproduction.
STAGE 4: REPLICATION
‘Replication’ of viruses is exactly what it sounds like: multiplication of the genome – the virus’ DNA or RNA, which are instructions for replicating new virus particles.
In essence, Replication comprises the first steps in creating new virus particles, and preparing them to be ‘Assembled’ into fully functional viruses, capable of attaching to new host cells and starting the cycle over, and so on.
STAGE 5: ASSEMBLY
Following the successful replication of the virus' genetic structure and the reproduction of the chemicals necessary to create a virus envelope to contain the genetic material of the newly created viruses, self-assembly (‘Virus Assembly’) of the virus particles is then completed, forming a whole new virus particle (think of these as ‘baby viruses’).
This process is sometimes referred to as ‘Maturation’, and is the last step in the virus replication process prior to the newly formed viruses being released into the system where they start the entire life cycle again, commencing with Attachment to a new host cell.
STAGE 6: RELEASE
Once newly formed and completed virus particles are fully replicated inside the host cell, they are ready to enter the body’s system and are ‘Released’ to start the life cycle process all over again with Attachment to a new, uninfected host cell.
Viruses can be released from the host cell by lysis, a process that kills the host cell by bursting its membrane and cell wall if present: this is a feature of many viruses. (Think of blowing up a balloon: at a certain point, the balloon cannot hold any more air, and it bursts open; now imagine a human cell exploding with newly formed virus particles.)
Some viruses, which in their completed state have a more substantial envelope coating the virus, may be released from the host cell through a process known as ‘Budding’.
During this process the virus acquires its envelope, which is a modified piece of the host’s plasma or other internal membrane or component of the host cell in which the virus has replicated itself.It is important to note that virus replication (completion of the entire life cycle) can happen very quickly, and result in the rapid proliferation of new virus particles; in many cases literally millions of newly formed virus particles are created and released into the system. Thus, the potential for infection (Attachment) of new host cells is quite substantial.
If the life cycle process is prevented, interrupted or interfered with, so that the viruses cannot initially attach to a target host cell, or cannot successfully complete their replication inside the host cell, or are prevented from being assembled or released, the virus life cycle may be cut short or stopped.
Research into all possible approaches to interfere with or impede the virus life cycle are actively being pursued, including drugs which can interfere with virus genetic replication, attempts to create vaccines which may prevent Virus Fusion, and the use of supplements to inhibit Virus Fusion are all key objectives of virus medicine and research.
In reality, there are many opportunities to reduce the likelihood of successful virus life cycle completion, starting with inhibiting the initial Virus Fusion – or Attachment to a host cell – to preventing completion of virus replication. Given that many viruses remain in the body forever, approaches that assist in keeping viruses dormant are also being developed, and may be assisted by various dietary, physical or life-style changes, and by using specific supplements that have been shown to have a damping effect on some stage of the virus life cycle.
REMEMBER THIS:
NO VIRUS ATTACHMENT = NO VIRUS REPRODUCTION!
*These statements have not been evaluated by the Food & Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease. Always seek professional medical attention for any medical conditions or health issues you may be experiencing. The information on this website is not intended as medical advice or to replace the advice of a qualified medical professional.
