The relatively high titer of anti-HPV16 antibodies at the cervix is promising in terms of vaccine efficacy; however, the decrease in antibody titer around ovulation raises the possibility that the HPV16 VLP vaccine might be less effective during the peri-ovulatory phase.

Immunization of mice with an attenuated Salmonella typhimurium strain (Phop c) carrying a plasmid encoding a hybrid form of the hepatitis B virus core antigen (HBc) induced specific antibody responses against the bacterial lipopolysaccharide (LPS) and HBc. Different mucosal routes of immunization, i.e., oral, nasal, rectal, and vaginal, were compared for their ability to induce a systemic as well as a mucosal response at sites proximal or distant to the site of immunization. Anti-LPS and anti-HBc immunoglobulin A (IgA) antibodies were measured in saliva, in feces, and in genital, bronchial, and intestinal secretions. Specific antibodies in serum and secretions were observed after immunization via all routes; however, the response to LPS was independent of that against HBc. In serum, saliva, and genital and bronchial secretions, high amounts of anti-HBc IgA were obtained by the nasal route of immunization. Vaginal immunization resulted in two different responses in mice: high and low. We observed a correlation between the level of specific immune response and the estrous status of these mice at the time of immunization. Rectal immunization induced high amounts of IgA against HBc and LPS in colonorectal secretions and feces but not at distant sites. These data suggest that S. typhimurium is able to invade different mucosal tissues and induce long-lasting local IgA responses against itself and a carried antigen after a single immunization.

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Attenuated strains of Salmonella are attractive live vaccine candidates for eliciting mucosal as well as systemic immune responses. The ability to induce immune responses in the reproductive tract may be critical for the effectiveness of a prophylactic vaccine against genital human papillomaviruses (HPV), which are important etiologic agents in the development of cervical cancer. To examine the potential of a live Salmonellabased vaccine to prevent genital HPV infection, the L1 major capsid protein from HPV type 16 (HPV16) was constitutively expressed in the PhoP c strain of Salmonella typhimurium. As demonstrated by electron microscopy, the L1 protein expressed in these bacteria assembled into virus-like particles (VLPs) that resemble authentic papillomavirus virions. This is the first demonstration that papillomavirus VLPs can self-assemble in prokaryotes. BALB/c mice were immunized with the HPV16 L1 recombinant PhoP c strain by the oral and nasal routes. Despite a low stability of the L1-expressing plasmid in vivo, a double nasal immunization was effective in inducing L1-specific serum antibodies that recognized mainly native, but not disassembled, VLPs. These antibodies effectively neutralized HPV16 pseudotyped virions in an in vitro infectivity assay. Conformationally dependent anti-VLP immunoglobulin A (IgA) and IgG were also detected in oral and vaginal secretions, indicating that potentially protective antibody responses were elicited at mucosal sites. Recombinant attenuated Salmonella expressing HPV capsids may represent a promising vaccine candidate against genital HPV infection.

Background and Objective A non‐touch laser‐induced microdrilling procedure is studied on mouse zona pellucida (ZP). Study Design/Materials and Methods A 1.48‐μm diode laser beam is focused in a 8‐μm spot through a 45× objective of an inverted microscope. Mouse zygotes, suspended in a culture medium, are microdrilled by exposing their ZP to a short laser irradiation and allowed to develop in vitro. Results Various sharp‐edged holes can be generated in the ZP with a single laser irradiation. Sizes can be varied by changing irradiation time (3–100 ms) or laser power (22–55 mW). Drilled zygotes present no signs of thermal damage under light and scanning electron microscopy and develop as expected in vitro, except for a distinct eight‐shaped hatching behavior. Conclusion The microdrilling procedure can generate standardized holes in mouse ZP, without any visible side effects. The hole formation can be explained by a local photothermolysis of the protein matrix. © 1996 Wiley‐Liss, Inc.