ANTI IL-17A TREATMENT IN MICE INFECTED WITH LACTATE DEHYDROGENASE ELEVATING VIRUS (LDV) CHANGE THE TITER AND ISOTYPES PROFILE OF SPECIFIC ANTIBODIES

MACARENA A. OTTOBRE SABORIDO; JOSÉ L. APARICIO

Jornada; VII JORNADA DE JOVENES INVESTIGADORES; 2018

LDV is a single stranded positivesense RNA enveloped arterivirus, is persistent, non pathogenic and induces NK,macrophages and B- cell activation in mice. It was found that LDV- infectionmodified Ab specificity to different antigens, depending on the geneticbackground of the host. This effect was correlated with the release of diversecytokines after viral infection recently. Recently, we have shown thatinhibition of a pro-inflammatory cytokine, interleukin 17A (IL-17A) induce amodification in the specificity of antibodies against conformational epitopesto a given antigen. The purpose of this work was to study, through ofmonoclonal antibody (MAb) treatment, the relation between the change ofspecificity in antibodies to an antigen such as, ovalbumin (OVA) and thevariation in the immunoglobulin isotype profile. C57BL/6 mice (n =18) were inoculated subcutaneously with25 μg of OVA emulsified in phosphate-buffered saline (PBS) and CompleteFreund?s Adjuvant. At day 15, the mice were boosted with the Ag in IncompleteFreund?s Adjuvant. At days 4, 7 and 11, half of the animals (n =9) were inoculated intraperitoneallywith 150 µg of MAb anti-IL-17A (MM17F3) in 200 µl of PBS. A group of mice (n =9) were treated as before but infectedwith 2×107 50% infectious doses of LDV in saline solution at day 0. Ascontrol, a group of mice (n = 5) were only infected with LDV and another group(n=4) without treatment. Bleeding was performed at days 8, 21, and 32. Thetiter of Ab anti-OVA was determined by Indirect ELISA, whereas the proportionof Ab directed to native OVA epitopes was calculated by ELISA competitionassays. The immunoglobulin isotypes (IgM, IgG1, IgG2a and IgG2b) were measured bySandwich ELISA.  Titers of anti-OVA Ab inLDV-infected animals decreased by MAb MM17F3 treatment (1/167000 ± 1/12600 to1/68000 ± 1/4700, for control and MAb treated mice, respectively, P<0.001).Besides, percent of native anti-OVA Ab in non-infected mice increased bytreatment with the MAb (48 to 61%, respectively). Same effect was shown in LDV-infected mice (65 to 87%, for control and treated animals, respectively).Theimmunoglobulin isotype profile in LDV-infected and OVA-inoculated animalsincreased by MAb treatment; IgM (43 to 49%, *P <0.05), IgG1 (50 to 57%,**P<0.01) and IgG2a (41 to 52%, **P<0.01) in relation to control mice(without MAb treatment). Whereas non-changes were observed in IgG2b isotypelevel as well as in non-infected animal treated. Results suggested that changein the specificity of Ab against conformational epitopes affected by IL-17A isrelated with an increase in the Ig isotype profile.