Reviewing fair subject selection considerations for the unique case of post sequelae COVID-19 translational studies.

Fair inclusion of research subjects is necessary to ensure that post-acute sequelae COVID-19 (PASC) research results benefit all members of society. Scientists should conduct research on a broad sample of individuals who represent clinically relevant factors influencing a disease. Without demographic diversity and sociological and environmental variability, research outputs are less likely to apply to different populations and would thus increase health disparities. The goal of this narrative literature review and ethical analysis is to apply fair selection criteria to PASC research studies. We briefly highlight the importance of fair subject selection in translational research and then identify features of PASC, as well as PASC research, that hinder fair inclusion of research participants. We will demonstrate that determining an adequate and representative sample is not simply a matter of ensuring greater diversity; rather, fairness requires a broader evaluation of risks, burdens, and benefits specific to underrepresented populations. We provide recommendations to ensure fair subject selection in PASC research and promote translation toward positive health outcomes for all individuals, including the most vulnerable.

Immune responses to Cryptosporidium muris and Cryptosporidium parvum in adult immunocompetent or immunocompromised (nude and SCID) mice.

Adult murine models of Cryptosporidium infection involving Cryptosporidium muris and C. parvum were used to study immunity to cryptosporidiosis in the mammalian host. Immunocompetent BALB/c or C57BL/6 mice developed a highly patent infection with the RN 66 strain of C. muris but overcame the infection and were immune to reinfection. In contrast, severe combined immunodeficiency (SCID) mice or nude mice had a chronic infection lasting at least 109 days. The development of the C. muris infection appeared to be confined to the gastric epithelium in immunocompetent and immunocompromised mice. SCID mice injected intraperitoneally with histocompatible spleen or mesenteric lymph node cells from uninfected BALB/c mice were able to recover from the C. muris infection. The protective effect of donor spleen cells was not reduced by depletion of the B cell population but was significantly reduced by depletion of Thy.1 cells. Treatment of C57BL/6 or BALB/c mice during infection with a gamma interferon-neutralizing monoclonal antibody, but not a tumor necrosis factor-neutralizing monoclonal antibody, resulted in a significant increase in oocyst production. In the C. parvum model, a severe and eventually fatal chronic infection with a cervine isolate was established in SCID mice, with parasitization occurring in the ileum, cecum, and colon. SCID mice injected with unprimed BALB/c spleen cells prior to inoculation of C. parvum oocysts were resistant to infection. These results suggested that the two animal models should be valuable in the study of immunity to cryptosporidial infection.

Comparative study of the antigenic composition of oocyst isolates of Cryptosporidium parvum from different hosts.

An investigation was made of the antigenic composition of oocyst isolates of Cryptosporidium parvum by immunoblotting using rabbit polyclonal or murine monoclonal antibodies (MoAbs) developed against this parasite. Using the polyclonal antibodies in blots, a common antigenic profile was obtained from a number of human oocyst isolates from AIDS patients and immunocompetent children in the UK and Portugal. Antigenic differences were observed, however, between a human isolate from Turkey and these other human isolates. The antigenic profiles of oocyst isolates from deer and cattle were similar, but the profiles of the animal and human isolates differed to some extent. Two MoAbs which, in immunofluorescence microscopy, reacted with the surface of the C. parvum sporozoite were also used in blots. A major antigen(s) from 9 of 11 human oocyst isolates recognized by these MoAbs had a molecular weight of 47 kD, but the sizes of the corresponding antigens of the remaining 2 human isolates, one from Turkey (same as above) and one from the UK, were 45.5 and 51 kD, respectively. The equivalent antigen(s) from 4 bovine and 4 ovine isolates was 48 kD. One of the MoAbs failed to react in blots with 2 of the isolates, 1 human and 1 bovine.

Characteristics and specificity of hybridoma antibodies against oocyst antigens of Cryptosporidium parvum from man.

Hybridoma antibodies (HAbs) against oocyst antigens of a human isolate of Cryptosporidium parvum were developed by fusion of SP2/0 mouse myeloma cells and spleen cells from BALB/c mice immunized with oocyst homogenates. In an indirect immunofluorescence antibody test (IFAT), using as antigen a mixture of air-dried sporozoites and oocysts, HAbs labelled either the oocyst wall or areas of the sporozoite, including the whole organism, the entire surface, a polar region or the interior. Most of the HAbs were specific for the sporozoite surface, and few of them recognized the oocyst wall. In Western blot analysis of oocyst antigens, sporozoite surface-reactive monoclonal antibodies (MoAbs) recognized one or more of seven polypeptide bands with molecular weights in the range 47- greater than 200 kD, and all reacted with the 47 kD band. Each of four heterologous parasite isolates had a unique recognition pattern with a panel of MoAbs in IFAT, suggesting antigenic differences may exist between strains of C. parvum. The ability to differentiate between parasite isolates by immunological methods might be of value in epidemiological studies of cryptosporidiosis.