There are various forms of influenza of influenza; those that have been identified include influenza A, influenza B, and influenza C. Type A usually results in causation of localized outbreaks seen in many places. Type B is known to cause sporadic occurrences of illnesses due to the viral mechanism, while type C is yet to be associated with major occurrences of illness conditions.
Role of Antigenic Shift and Antigenic Drift
There are fundamental differences between antigenic drift and antigenic shift in the contemporary study of influenza virus:
Antigenic shift primarily occurs when different strains (in essence more than two) interact leading to the subsequent formation of new subtype with an expression of different formulation of antigens. Antigenic shift occurs fro accumulation of new epitopes on the H protein of the virus (Shors, 2008). Therefore, this implies that the interacting strains lead to the production of a variant strain having phenotypically different characteristics. “Provided that the reassortant virus is efficiently transmissible from infected to non-infected hosts, such an antigenically novel virus strain has pandemic potential when introduced in a population that completely lacks immunity against the new surface protein” (Fong & Alibek, 2007). In nature, antigenic shift may occur in different kinds of hosts. The most preferred host for the actual reassortment of the influenza is the pig due to resultant susceptibility to human and avian strains (Fong & Alibek, 2007). Antigenic shift usually leads to an occurrence of potential pandemic due to the rapid spread and replication of the strain produced.
“Antigenic drift is the small changes in the H and N genes that happen over time. It produces new virus strains that may not be recognized by the body’s immune system, necessitating changes in the influenza vaccines” (Shors, 2008). Ordinarily, when one gets infected with a strain of influenza virus, the body reacts through the production of antigens. When new strains appear, the previous antigens are unable to recognize those necessitating systemic changes, and this is usually responsibly for localized outbreaks (Shors, 2008).
Hemagglutinin and Neuraminidase & their Use in Tracking Influenza
In ordinary occurrences, infections are known to posses various intrinsic forms or strains of infection markers, which are primarily used to identify infections occurring in a species. The effectiveness of the markers is track down illnesses to the initial source of the infection. This also applies primarily in the case of influenza virus as seen in many recurring cases of illnesses in clinical settings. “Influenza A virus is the classic example, with periodic major changes (shift) occurring in either or both critical surface antigens, hemagglutinin and neuraminidase, associated with the pandemic disease and progressive minor change in hemagglutinin in the interpandemic period” (Feign, 2004). Hemmagglutinin (H) and Neuraminidase (N) are essentially integral protein membranes occurring within the lipid double layer. Hemagglutinins and Neuraminidase usually occur in various forms, for instance, Hemaglutinins occur may occur as H1, H2 and H3 forms, while Neuraminidase may occur as N1 and N2 forms. The identification of these forms in the occurring influenza infections are primarily used in the tracking of specific variant of influence, for instance, occurrence of H1N1.
Why do we study influenza virus
Influenza virus is primarily studied in microbiological and immunological science in a bid to establish the occurring forms of influenza virus. The major concern in regard to influenza is the manner in which the influenza virus is known to replicate itself leading to the formation of variant forms that lead to localized cases of influenza infection and other potentially infectious forms of influenza capable of causing major reactions. The cases of influenza pandemics have resulted into many deaths. For instance, in April 2009 a virus containing a combination of swine and human influenza viruses resulted in A(H1N1) strain in over 40 countries, with 74 deaths being caused and over 8829 laboratory confirmed cases (WHO Collaborating Centre for Influenza et al, 2009). This therefore shows the importance of influenza virus among current important diseases in the constantly evolving epidemiology.