Immunization with a Mixture of Nucleoprotein from Human Metapneumovirus and AbISCO-100 Adjuvant Reduces Viral Infection in Mice Model.

The human metapneumovirus (hMPV) is the second leading cause globally of acute infection of the respiratory tract in children, infecting the upper and lower airways. The hMPV may induce an inappropriate Th2-type immune response, which causes severe pulmonary inflammation, leading to the obstruction of airways. Despite its severe epidemiological relevance, no vaccines are currently available for the prevention of hMPV-induced illness. In this investigation, we demonstrated that immunization of mice with the recombinant hMPV nucleoprotein (hMPV-N) mixed with the AbISCO-100 adjuvant reduced viral replication in lungs following challenge with the virus. We found that immunized mice had reduced weight loss, decreased granulocytes in the lung, an increased level of specific nucleoprotein antibodies of IgG1 and IgG2a-isotypes, and a local profile of Th1/Th17-type cytokines. Our results suggest that immunization with the hMPV-N and the AbISCO-100 adjuvant induces a reduction of viral infection and could be considered for the development of an hMPV vaccine.

Production and characterization of monoclonal antibodies against the recombinant nucleoprotein of Araucaria hantavirus.

Hantaviruses are rodent-borne RNA viruses that cause hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). From the first detection of infection in Brazil in 1993 until 2009, 1161 cases of HPS have been reported, with mortality rates of around approximately 40%. Currently, due to the absence of a vaccine or specific antiviral therapy, the only way to reduce mortality by hantavirus infection is a fast and precise diagnosis that allows for supportive clinical health care. To improve the detection of hantavirus infection, we developed monoclonal antibodies (Mabs) against the nucleoprotein (rNDelta85) of the Araucaria hantavirus strain (ARAUV). The specificity of generated Mabs for rNDelta85 was demonstrated by western blot, indirect immunofluorescence and immunohistochemistry. These are the first monoclonal antibodies to be produced and characterized against the South American hantavirus strain, and may be of special interest in the development of diagnostic assays and epidemiological studies.

Comparison of immunoglobulin G subclass profiles induced by measles virus in vaccinated and naturally infected individuals.

A total of 258 human sera positive for measles antibodies were divided into four different groups: group 1 contained 54 sera from children after natural measles infection (immunoglobulin M [IgM] positive, early infection phase), group 2 contained 28 sera from children after measles vaccination (IgM positive, early infection phase), group 3 contained 100 sera from healthy adults (natural long-lasting immunity), and group 4 contained 76 sera from healthy children (postvaccinal long-lasting immunity). In the early phase of infection, the percent distributions of measles virus-specific IgG isotypes were similar between natural and postvaccinal immune responses. IgG1 and IgG4 were the dominant isotypes, with mean levels of detection of 100% (natural infection) and 100% (postvaccinal) for IgG1 and 96% (natural infection) and 92% (postvaccinal) for IgG4. In comparison, the IgG4 geometric mean titer (GMT) in the early phase of natural infection was significantly higher than the IgG4 GMT detected in the postvaccinal immune response (80 versus 13; 95% confidence interval). In the memory phase, IgG2 and IgG3 responses decreased significantly in both natural infection and postvaccinal groups, while IgG1 levels were maintained. In contrast, the IgG4 postvaccinal immune response decreased strongly in the memory phase, whereas IgG4 natural long-lasting immunity remained unchanged (9 versus 86%; P < 0.05). The results obtained suggest that IgG4 isotype could be used in the early phase of infection as a quantitative marker and in long-lasting immunity as a qualitative marker to differentiate between natural and postvaccinal immune responses.

Total and isotype humoral responses in cattle vaccinated with foot and mouth disease virus (FMDV) immunogen produced either in bovine tongue tissue or in BHK-21 cell suspension cultures.

The anti-foot and mouth disease virus (FMDV) serum antibody activity of protected and non protected animals immunized with inactivated FMDV originated in either bovine tongue tissue (BTTV vaccines) or BHK-21 cell suspension cultures (BHKV vaccines) was evaluated. The results show that 80-100% of the BTTV immunized and only 40-60% of the BHKV immunized animals with liquid-phase blocking sandwich ELISA (lp ELISA) serum titres of 1.5-1.7 U, were protected against the challenge with any of the four infectious FMDV argentine reference strains. This difference becomes almost marginal among BTTV and BHKV vaccinated animals with a strong anti-FMDV humoral response (i.e. lp ELISA titres > or = 1.95 U). Isotyping of the anti-FMDV response in immunized cattle with low lp ELISA titres revealed that BTTV vaccines were able to induce remarkably higher anti-FMDV IgG1 titres than their BHKV counterparts (i.e. mean titres of 1.95 and 1.35 U. respectively). This difference in specific IgG1 serum levels induced by BTTV and BHKV vaccines seems to be also limited to those animals with low anti-FMDV lp ELISA titres. These results together with the fact that the specific serum IgG1, but not the IgG2, isotype response of 219 vaccinated animals correlates almost linearly with their capacity to pass the challenge, suggests that the superior performance of BTTV vaccines is close related to their ability to raise a stronger anti-FMDV IgG1 response than BHKV vaccines.

[Humoral immune response in cattle vaccinated against aphthovirus. Study of the kinetics of protective and neutralizing antibodies]. / Respuesta inmune humoral en bovinos vacunados contra aftovirus. Estudio de la cinética de anticuerpos protectores y neutralizantes.

The sera of three groups (I, II and III) of cattle vaccinated every three months with trivalent hydroxysaponinated commercial vaccine against aphthovirus were studied. The only difference between groups I and II was that the former received a revaccination on day 17 after the initial immunization. Groups I and II included sera from animals three months old born from vaccinated mothers. Group III consisted of the sera of adult animals (the mothers of animals in groups I and II). The animals from the three groups were bled monthly during one year. The studies were performed with pooled sera from each group. The presence of protective and neutralizing antibodies was investigated in the gammaglobulin fractions which were then separated into subclasses, by chromatography on DE-cellulose columns, in order to study their biological activity. The immunization of cattle 3 months old with commercial vaccine against aphthovirus resulted in weak primary humoral response; neutralizing antibodies could not be detected. When the animals were restimulated three weeks after the first immunization, neutralizing antibodies appeared although the response did not persist. Nevertheless, five months after the experiment was started both groups I and II showed neutralizing antibodies. (Fig. 1, 2, 3). Persistent immunity to the three virus subtypes was acquired by animals of groups I and II but not before nine months. The kinetics of protective antibodies was similar to that of neutralizing antibodies, but with higher titers. Some bleedings that did not show neutralizing activity, did show significant protective activity (Figs. 4, 5). The investigation of the neutralizing activity of the gammaglobulin subclasses obtained by chromatography revealed that there was not one single subclass responsible for this activity, but that several subclasses were involved. The gammaglobulin subclasses were analyzed by immunoelectrophoresis; proteins with alpha 2 mobility appeared, coincident with early bleedings of high neutralizing titers, although these proteins did not present neutralizing activity (Tables 1, 2). The protective and neutralizing activity was not correlated with the protein concentration of the fractions so that the increase observed may be due to a qualitative change in the antibodies.