[Para-aminobenzoic acid in therapy of experimental keratitis caused by herpes simplex virus in rabbits: the therapeutic effect and decrease of infectious titer]

Para-aminobenzoic acid (PABA) in low concentrations exerted an antiherpetic effect with a good therapeutic result in rabbits with experimental keratoconjunctivitis caused by herpes simplex virus (HSV) (experimental group). In group 2 (control) 0.9% NaCl solution was used as placebo. The animals were infected by instillation of HSV-1 on the cornea predissected with a bifurcation needle. The severity of keratitis was assessed in scores after A. A. Kasparov et al. PABA and placebo were administered starting from day 3 postinfection as subconjunctival injections and then instillations. In experimental group (5 rabbits, 10 eyes) the degree of keratitis reduced from 3.0 +/- 0.2 to 1.7 +/- 0.1 points within the first 4 days. Complete epithelialization was over by day 4.4 +/- 0.4, clinical cure was attained by days 12-13. In control group (6 rabbits, 12 eyes) erosion of the cornea and severity of keratitis increased from 2.9 +/- 0.07 to 3.8 +/- 0.2 points by day 4 postinoculation after placebo was started, after which it reduced; epithelialization was over by day 8.2 +/- 0.3, clinical cure by days 13-14. Infective titer in the cornea was determined in VERO cell culture from the degree of virus-induced cytopathogenic effect and expressed in lgTCE50. On day 13 this parameter was reliably higher in the control group in comparison with the experimental (3.2 vs. 1.8), this confirming the virucidal effect of PABA.