A Mouse Model to Study the Pathogenic Transition of Streptococcus pneumoniae Following Viral Co-Infection

Begin with biofilm-grown Streptococcus pneumoniae, an asymptomatic nasopharyngeal colonizer, suspended in a buffer

Intranasally administer the suspension to an unanesthetized mouse, allowing inhalation into the upper respiratory tract.

In the nasopharyngeal epithelium, the bacteria establish a biofilm that facilitates colonization and suppresses antiviral cytokine production from host cells.

After anesthetization, extend the mouse’s tongue to access the trachea.

Administer the influenza A virus into the trachea to infect the lower respiratory tract.

After the mouse recovers, immediately inoculate the virus intranasally to target the upper respiratory tract.

Viral infection dysregulates the host immune system and damages mucosal tissue, triggering bacterial dispersal into the lower respiratory tract.

In the virus-altered lung environment, the bacteria transition into invasive pathogens, inducing pulmonary inflammation and systemic spread.

The infection also suppresses neutrophil function, reducing bacterial clearance.

This co-infection model enables investigation of host-microbial interactions.

Thaw the biofilm grown aliquots on ice and spin at 1,700 g for five minutes. Carefully remove and d