This week, I am introducing two more viruses from the family Orthomyxoviridae and Picornaviridae.

What’s that with a name so long?

Well, they are actually RNA viruses from the family which cause us Flu and cold respectively.

I shall start explaining from Picornaviridae family.



Picornaviridae are the largest virus family with over 230 serotypes and 9 genera such as Enterovirus, Heptovirus and the Rhinovirus. (If the Rhinovirus sounds familiar, it is actually the virus, WANTED for your common cold!)

The Picornaviridae doesn’t have any envelope and it is a one linear positive RNA virus. With other ends modified, its capsids are mostly empty or uncompleted!
As I go into more of the Rhinovirus; it infects you by infecting the upper respiratory tract as it will not be able to grow as fast in 37 °C and incubates for a short period of around 2 to 3 days before any symptoms for it arise. And once the virus infects our cells and is detected by our antibodies, our locally synthesized IgA would defend itself against the virus. After “defeating” the virus, serum IgG would remain in your blood, which can stay up to your lifetime, to defend itself from any future infection of that virus. However, your body is still at risk of being infected again as there are over 100 rhinoviruses in the world!


As you can see, many of us “usually mistaken cold as flu” as they have similar symptoms! Normally, symptoms such as watery nasal discharge, difficulty breathing through your nose, and sneezing could be seen in patients diagnose with common cold.And Another more accurate diagnose could be done through nasal washings and virus culture as the IgA could be seen and detected from the blood sample.

Talking about flu virus, it is from the virus family Orthomyxoviridae.

Since 430 B.C. there has been report of the influenza epidemic in Athens. But luckily, only 2 types of influenza virus, A and B would cause hectic in humans.
With spikes envelope and single strand negative RNA in 8 segments; Orthomyxoviridae is capable of “changing” its genes every now and then. It also infects the respiratory tract in humans and can be diagnose by the antibodies in blood sample through nasal wash or virus culture in chick embryo. With a longer incubation period of 1 to 4 days, its 8 segments of the genome enable it to actively assort its genes and causing mutation, resulting in new subtypes and new strain.
Antigenic shift normally results in only a small change in the genome, signaling mutation and a new strain which happens most of the time. While an antigenic shift is a major change of the gene, resulting in a new subtype but it happens only once every 10 to 40 years. An example of such antigenic changes is the avian flu which since its outbreak in 1997 have caused 248 deaths in 12 countries as of January 2009 from the WHO


Both virus, Orthomyxoviridae and Picornaviridae can be found abundant in nasal discharge and to combat both common cold and flu, and not to ruin your festive mood (as both common cold and flu are really common during festive seasons!) it is best to washing your hands regularly, practicing healthy habits and preventing inhaling drops of mucus full of rhinovirus from the air when a suspected contagious person coughs or sneezes! As for both of the virus, they have useless effects on vaccines. As cold have over a hundred of types, it is almost impossible to produce so many different vaccines for each of the types because it is considered to have no economic benefits. On the other hand for flu, the antigenic drift and shift that occurs are too fast to occur for vaccines to be produced.

Below, is a video on the avian flu, H5N1 virus, explained by a veterinarian