Human cytomegalovirus serum neutralizing antibodies block virus infection of endothelial/epithelial cells, but not fibroblasts, early during primary infection

Abstract

A panel of human sera exhibited a ¢128-fold higher neutralizing potency against a human cytomegalovirus (HCMV) clinical isolate propagated and tested in endothelial (or epithelial) cells than against the same virus infecting human fibroblasts. In a group of 18 primary infections, the reverse geometric mean titre was in the range of 10-15 in human fibroblasts within the first 3 months after the onset of infection, whereas the endothelial cell infection-neutralizing activity was already present within the first 10 days, reaching median levels of 122, 320 and 545 at respectively 30, 60 and 90 days after onset, then declining slowly. This difference was also confirmed in the majority of reactivated and remote HCMV infections, as well as in a hyperimmune globulin preparation. The antibody response to HCMV pUL131A, pUL130 and pUL128 locus products, which are required for endothelial/epithelial cell infection, provided a potential molecular basis for such a differential neutralizing activity. In addition, monoclonal/monospecific antibodies raised against the pUL131A, pUL130 and pUL128 proteins were found to display an inhibitory activity on HCMV plaque formation and HCMV leukocyte transfer from HCMV-infected cells. Hence, conventional determination of the neutralizing activity of human sera in fibroblasts is misleading. Antibodies to pUL131A, pUL130 and pUL128 appear to display a major HCMV-neutralizing and dissemination-inhibiting activity.

A Randomized Trial of Hyperimmune Globulin to Prevent Congenital Cytomegalovirus

“…19,20 As confirmed in this study, these neutralizing antibodies are produced and peak very early after the onset of primary infection, without a clear difference between mothers who transmit the virus and mothers who do not. 12,21 On the other hand, neutralizing antibodies against AD169 are slower to develop, 12,21,22 and in our study, administration of hyperimmune globulin did not significantly modify their levels. Similarly, hyperimmune globulin did not significantly modify maternal levels of DNA in the blood or the time to clearance of DNA from the blood, nor did it significantly modify DNA levels in placentas.…”

“…Neutralizing antibodies against the AD169 strain of CMV in human fibroblasts and the VR1814 strain of CMV in epithelial (spontaneously arising retinal pigment epithelial [ARPE]-19) cells were assessed as described previously. 12 Viral DNA in the blood was determined with the use of a real-time polymerase-chain-reaction (PCR) assay (CMV ELITe MGB Kit, ELITechGroup). Positive samples with less than 396 IU per milliliter were assigned an arbitrary value of 200 IU.…”

Differential kinetics of human cytomegalovirus load and antibody responses in primary infection of the immunocompetent and immunocompromised host

“…HCMV isolate VR1814 was used for assays in ARPE-19 cells, while laboratory strain AD169 was used for assays in HELF cells. The differential neutralizing activity of human sera when tested in ARPE-19 or HELF cells was previously reported (Gerna et al, 2008).…”

“…The double neutralization assay was based on the recent discovery that HCMV requires the pentamer to infect epithelial/endothelial/dendritic cells Ryckman et al, 2008), while infection of HELF cells requires the presence of gH/gL/gO on the HCMV envelope (Zhou et al, 2013). It has been demonstrated and repeatedly confirmed that neutralizing titres determined in epithelial cells are far higher than those obtained in HELF cells (Cui et al, 2008;Gerna et al, 2008).…”

“…In addition, gB-based vaccines have shown only partial protection against vertical HCMV transmission in pregnant women and against HCMV infection in transplanted patients (Pass et al, 2009;Griffiths et al, 2011). Furthermore, neutralizing antibodies have been shown to display far higher titres when measured in epithelial rather than fibroblast cells (Cui et al, 2008;Gerna et al, 2008).…”