Lack of association between feline AB blood groups and retroviral status: a multicenter, multicountry study

Discordance between ABC blood phenotype and genotype in a domestic short-haired cat

An adult domestic short-haired feline leukemia virus-infected cat was referred for kidney failure and worsening anemia requiring transfusions. ABC blood typing was performed with an immunochromatographic strip assay at different occasions. Gel column systems were used for the major and minor crossmatching tests, and anti-A and anti-B titers were determined. No discrete A or B bands appeared on the immunochromatographic strips at any time point for the recipient cat. The recipient's plasma agglutinated RBCs from tested type A and B cats. The recipient's RBCs appeared compatible with plasma from 1 type A and 2 B donors, and incompatible with plasma from another type A cat. Genotyping of recipient blood revealed a single homozygous c.179G>T CMAH variant predicting a blood type B. These studies suggest an unusual weak type B or missing all ABC antigens. The latter resembles the exceedingly rare Bombay phenotype in the human ABO blood group system.

Do Blood Phenotypes of Feline AB Blood Group System Affect the SARS-CoV-2 Antibody Serostatus in Cats?

Cats are susceptible to coronavirus infections, including infection by human severe acute respiratory syndrome coronavirus (SARS-CoV). In human ABO system blood groups, alloantibodies can play a direct role in resistance to infectious diseases. Individuals with the AB blood type were over-represented in the SARS-CoV-2 infection group. Blood type AB individuals lack both anti-A and anti-B antibodies, and therefore lack the protective effect against SARS-CoV-2 infection given by these antibodies. Starting from this knowledge, this pilot preliminary study evaluated a possible association between feline blood phenotypes A, B, and AB and serostatus for SARS-CoV-2 antibodies in cats. We also investigated selected risk or protective factors associated with seropositivity for this coronavirus. A feline population of 215 cats was analysed for AB group system blood phenotypes and antibodies against the nucleocapsid (N-protein) SARS-CoV-2 antigen using a double antigen ELISA. SARS-CoV-2 seropositive samples were confirmed using a surrogate virus neutralization test (sVNT). Origin (stray colony/shelter/owned cat), breed (DSH/non DSH), gender (male/female), reproductive status (neutered/intact), age class (kitten/young adult/mature adult/senior), retroviruses status (seropositive/seronegative), and blood phenotype (A, B, and AB) were evaluated as protective or risk factors for SARS-CoV-2 seropositivity. Seropositivity for antibodies against the SARS-CoV-2 N-protein was recorded in eight cats, but only four of these tested positive with sVNT. Of these four SARS-CoV-2 seropositive cats, three were blood phenotype A and one was phenotype AB. Young adult age (1-6 years), FeLV seropositivity and blood type AB were significantly associated with SARS-CoV-2 seropositivity according to a univariate analysis, but only blood type AB (p = 0.0344, OR = 15.4, 95%CI: 1.22-194.39) and FeLV seropositivity (p = 0.0444, OR = 13.2, 95%CI: 1.06-163.63) were significant associated risk factors according to a logistic regression. Blood phenotype AB might be associated with seropositivity for SARS-CoV-2 antibodies. This could be due, as in people, to the protective effect of naturally occurring alloantibodies to blood type antigens which are lacking in type AB cats. The results of this pilot study should be considered very preliminary, and we suggest the need for further research to assess this potential relationship.

Evaluating the association between blood genotype or phenotype and haemoplasma infection in UK and Italian cats

BACKGROUND

In humans, blood groups are associated with varying prevalence of infections. The aim of this study was to determine if associations exist between the feline AB blood group system and haemoplasma infection.

METHODS

Data from two studies were combined. In the first study, DNA samples from 131 haemoplasma-infected and 132 haemoplasma-uninfected UK cats underwent pyrosequencing to determine their blood genotype as AA, Ab or bb. In the second study, blood samples from 160 Italian cats of known blood phenotype A, B or AB underwent PCR testing for feline haemoplasma species DNA.

RESULTS

Haemoplasma infection was demonstrated in cats of all phenotypes and genotypes. A significantly higher number of Ab genotype cats tested positive for overall haemoplasma infection status (p = 0.04) and for Mycoplasma haemofelis infection (p = 0.03).

LIMITATIONS

Haemoplasma-infected Italian cats were few, possibly increasing the chance of type II error, and the presence of purebred cats in the sample population may have had a confounding effect.

CONCLUSIONS

Feline haemoplasmas do not appear to preferentially use either blood type A or B antigens as attachment sites for erythrocyte colonisation. Further investigations in a larger number of haemoplasma-infected cats of known blood phenotype are warranted to explain the association between genotype Ab and haemoplasma infection.

Evaluation of Association between Blood Phenotypes A, B and AB and Feline Coronavirus Infection in Cats

Cats are susceptible to feline coronavirus (FCoV), a highly contagious virus with fecal–oral transmission. In people, susceptibility to coronavirus infection, such as SARS-CoV infection, has been associated with the ABO blood group, with individuals with blood group O having significantly lower risk of SARS-CoV infection. This study evaluated a possible association between feline blood group phenotypes A, B and AB and serostatus for antibodies against FCoV. We also investigated risk or protective factors associated with seropositivity for FCoV in the investigated population. Feline populations were surveyed for AB group system blood types and for presence of antibodies against FCoV. Blood phenotype, origin, breed, gender, reproductive status and age of cats were evaluated as protective or risk factors for coronavirus infection. No blood type was associated with FCoV seropositivity, for which being a colony stray cat (p = 0.0002, OR = 0.2, 95% CI: 0.14–0.54) or a domestic shorthair cat (p = 0.0075, OR = 0.2, 95% CI = 0.09–0.69) were protective factors. Based on results of this study, feline blood phenotypes A, B or AB do not seem to predispose cats to seropositivity for FCoV. Future studies on other feline blood types and other infections could clarify whether feline blood types could play a role in predisposing to, or protecting against, feline infections.