Genetic variability in G2 and F2 region between biological clones of human respiratory syncytial virus with or without host immune selection pressure

Human respiratory syncytial virus (HRSV) is an important respiratory pathogens among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. Only one of these clones was obtained after treatment with the child's serum. In addition, some synonymous mutations were determined in two clones of the HRSV-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.

Gestation and breastfeeding in schistosomotic mothers differently modulate the immune response of adult offspring to postnatal Schistosoma mansoni infection

Schistosoma mansoni antigens in the early life alter homologous and heterologous immunity during postnatal infections. We evaluate the immunity to parasite antigens and ovalbumin (OA) in adult mice born/suckled by schistosomotic mothers. Newborns were divided into: born (BIM), suckled (SIM) or born/suckled (BSIM) in schistosomotic mothers, and animals from noninfected mothers (control). When adults, the mice were infected and compared the hepatic granuloma size and cellularity. Some animals were OA + adjuvant immunised. We evaluated hypersensitivity reactions (HR), antibodies levels (IgG1/IgG2a) anti-soluble egg antigen and anti-soluble worm antigen preparation, and anti-OA, cytokine production, and CD4+FoxP3+T-cells by splenocytes. Compared to control group, BIM mice showed a greater quantity of granulomas and collagen deposition, whereas SIM and BSIM presented smaller granulomas. BSIM group exhibited the lowest levels of anti-parasite antibodies. For anti-OA immunity, immediate HR was suppressed in all groups, with greater intensity in SIM mice accompanied of the remarkable level of basal CD4+FoxP3+T-cells. BIM and SIM groups produced less interleukin (IL)-4 and interferon (IFN)-g. In BSIM, there was higher production of IL-10 and IFN-g, but lower levels of IL-4 and CD4+FoxP3+T-cells. Thus, pregnancy in schistosomotic mothers intensified hepatic fibrosis, whereas breastfeeding diminished granulomas in descendants. Separately, pregnancy and breastfeeding could suppress heterologous immunity; however, when combined, the responses could be partially restored in infected descendants.

The mc2-CMX vaccine induces an enhanced immune response against Mycobacterium tuberculosis compared to Bacillus Calmette-Guérin but with similar lung inflammatory effects

Although the attenuated Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccine has been used since 1921, tuberculosis (TB) control still proceeds at a slow pace. The main reason is the variable efficacy of BCG protection against TB among adults, which ranges from 0-80%. Subsequently, the mc2-CMX vaccine was developed with promising results. Nonetheless, this recombinant vaccine needs to be compared to the standard BCG vaccine. The objective of this study was to evaluate the immune response induced by mc2-CMX and compare it to the response generated by BCG. BALB/c mice were immunised with both vaccines and challenged withMycobacterium tuberculosis (Mtb). The immune and inflammatory responses were evaluated by ELISA, flow cytometry, and histopathology. Mice vaccinated with mc2-CMX and challenged with Mtb induced an increase in the IgG1 and IgG2 levels against CMX as well as recalled specific CD4+ T-cells that produced T-helper 1 cytokines in the lungs and spleen compared with BCG vaccinated and challenged mice. Both vaccines reduced the lung inflammatory pathology induced by the Mtb infection. The mc2-CMX vaccine induces a humoral and cellular response that is superior to BCG and is efficiently recalled after challenge with Mtb, although both vaccines induced similar inflammatory reductions.