The phrase "a sample of sera" is correct and usable in written English.
It can be used in scientific or medical contexts when referring to a specimen of serum, which is the clear fluid that separates from blood when it clots.
Example: "The researchers collected a sample of sera from the patients to analyze their immune response."
Alternatives: "a specimen of serum" or "a serum sample".
Besides this, a random sample of sera of beef animals were tested since 1993 (see Table 2).
Toward this end, 1 was immobilized on sepharose, and a pooled sample of sera that exhibited high reactivity toward 1 was passed over the column.
We documented clinical features in all children and tested for prior antibiotic use in a random sample of sera from children from each site.
Sixty-five sera were aliquots from a larger sample of sera previously analyzed and stored within the regional monitoring plan for African swine fever (ASF) and Classical swine fever (CSF) enforced in Sardinia, in compliance with the European Community requirements.
In Australia, a sample of 723 human sera from patients from a dairy and pig-producing area of Victoria, all of whom had symptoms consistent with leptospirosis, was submitted for leptospirosis serologic testing.
Based on antibody titers by ELISA on day 84, a representative sample of fifteen sera was selected for IFA, containing at least two samples from each adjuvant group and at least three samples with low, intermediate or high ELISA titers.
We obtained samples of sera from patients who had a history of asthma and had a positive skin prick test to house dust mites (DM).
For validating this assay, 140 clinical samples of sera were used, comprising 100 samples from patients who tested positive for anti-HDV and hepatitis B virus surface antigen (HBsAg) by ELISA; 30 samples from blood donors; 5 samples monoinfected with hepatitis B virus (HBV); and 5 samples monoinfected with hepatitis C virus (HCV).
Serially diluted (2-fold increments) samples of sera and BAL fluid, as indicated in the figures, were used to derive the antibody titration curves.
Field samples of sera from bovine TB or MAP infected animals were obtained from serum repositories at National Veterinary Services Laboratory or from routine sample acquisitions into Minnesota Veterinary Diagnostic Laboratory, respectively.
