Table 1.

Characteristics of various modes of transmission

Route of Transmission		Epithelial Barrier	Target Cell Availability	Key Advantages	Limitations	Selected References
Rectal		Columnar	Abundant	Most widely used infection route, consistent infection rate, requires limited dose, primary site of infection in developed countries	Frequently overdosed, atraumatic model only	[31,32,41]
Female Genital Tract	Vagina/Ectocervix Endocervix	Squamous Columnar	Abundant Limited	Widely used infection route, modeling the most frequent mode of infection globally	Inconsistent infection rate, typically includes monitoring menstrual cycle, requires significant inoculum dose	[33,44,45]
Male Genital Tract	Foreskin Urethra	Keratinized Squamous Columnar	Limited Limited	Recently developed as a transmission model, frequent site of male infections	Technically challenging to perform, requires significant inoculum dose	[34,46–48]
Oral		Squamous & Columnar	Variable	Understudied, but important site of transmission	Logistically challenging to establish model	[49,50]
Non Mucosal		No Barrier	Abundant	Consistent infection rate, simple to administer	Typically not used to model transmission	--