Male infertility can have different causes, one of which may be the presence of etiologic agents that cause sexually transmitted infections. Among the most important sexually transmitted infections are human papillomavirus and Chlamydia trachomatis, which are associated with infertility in females -whether they cause infertility in men is controversial. The purpose of the chapter is to review the effect of these two pathogens on male fertility, the evidence suggests that the most important infertility effect is linked to the condition of the sperm. However, it is noteworthy that there are few studies with respect to infertility in regard to both pathogens, so it is important to further research this to elucidate the mechanisms by which these pathogens act on male infertility.

RESUMEN.-La saliva tiene potencial para ser un instrumento de diagnóstico, asimismo se espera que su uso como herramienta de diagnóstico aumente de manera exponencial en los próximos años. Nuestro objetivo principal fue estudiar el perfil de expresión génica de dos de los genes constitutivos más comunes en saliva, gliceraldehído-3-fosfato deshidrogenasa (GAPDH) y 18S, en muestras de quince voluntarios sanos. Comparamos el valor CT, que se define como la intersección entre una curva de amplificación y una línea de umbral. De acuerdo con el análisis realizado, no hay ninguna diferencia estadísticamente significativa entre ambos genes. PALABRAS CLAVES: expresión génica, genes constitutivos, gliceraldehído-3-fosfato deshidrogenasa (GAPDH), saliva, 18S ARNr ABSTRACT.-Saliva has a potential to be a diagnostic instrument, also it is expected that its use as a diagnostic tool will increase exponentially in the next few years. Our main aim was to study the gene expression profile of two of the most common constitutive genes in saliva, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and 18S rRNA, in samples of 15 healthy subjects. We compared the CT value, which is defined as the intersection among an amplification curve and a threshold line. According to the analysis, there is no statistically significant difference between the two genes.