The effect of heterogeneous hyperimmune IgG antibody on prophylaxis and treatment of Pneumocystis carinii infection in rats

Geographical variation in serological responses to recombinant Pneumocystis jirovecii major surface glycoprotein antigens

The use of recombinant fragments of the major surface glycoprotein (Msg) of Pneumocystis jirovecii has proven useful for studying serological immune responses of blood donors and human immunodeficiency virus (HIV)-positive (HIV(+)) patients. Here, we have used ELISA to measure antibody titres to Msg fragments (MsgA, MsgB, MsgC1, MsgC3, MsgC8 and MsgC9) in sera isolated in the USA (n=200) and Spain (n=326), to determine whether geographical location affects serological responses to these antigens. Blood donors from Seville exhibited a significantly greater antibody titre to MsgC8, and significantly lower responses to MsgC3 and MsgC9, than did Cincinnati (USA) donors. Spanish blood donors (n=162) also exhibited elevated responses to MsgC1, MsgC8 and MsgC9 as compared with Spanish HIV(+) (n=164) patients. HIV(+) patients who had Pneumocystis pneumonia (PcP(+)) exhibited a higher response to MsgC8 than did HIV(+) PcP(-) patients. These data show that geographical location plays a role in responsiveness to Msg fragments. Additionally, these fragments have utility in differentiating HIV(+) PcP and HIV(+) PcP(+) among patient populations.

Human immunodeficiency virus-infected patients with prior Pneumocystis pneumonia exhibit increased serologic reactivity to several major surface glycoprotein clones

Recombinant clones of the carboxyl terminus of the major surface glycoprotein (MsgC) of Pneumocystis jirovecii are useful for analyzing serologic responses in humans. However, there is no standardized set of antigens in general use, which could lead to conflicting results. We have previously shown that human immunodeficiency virus type 1 (HIV-1)-infected patients with prior Pneumocystis pneumonia (PcP+) responded more frequently and more strongly to a clone of MsgC than did HIV-1-infected patients without PcP (PcP-). Here we test three new clones of MsgC to determine the effect of antigenic sequence variation on immune reactivity in blood donors and HIV-infected patients previously analyzed for reactivity to our original MsgC clone. In Western blot analyses, PcP+ patients exhibited the highest frequency of reactivity to each MsgC clone, and the frequency of reactivity with all four MsgC clones together was significantly higher in sera from PcP+ patients than in sera from the other patient groups. Furthermore, in an enzyme-linked immunosorbent assay we found that the PcP+ population had the highest level of reactivity to two of the four clones tested. One of the new clones could distinguish between PcP+ and PcP- populations, and two MsgC clones could distinguish blood donors from the other patient populations. The results show that inherent differences in MsgC amino acid sequence can affect recognition by antibodies independently of variations in protein length or patient population, and the utility of a clone depends on its sequence and on the populations tested.