3.5 Detection of Viral load
Using standard DNA, the qPCR assay detection limit was estimated to be
9.1 copies per reaction and the slope and correlation coefficient of the
standard curve were −2·557 and 0·981 respectively (Figure 3). HAdV
genome was detected by qPCR in all 61 PCR positive samples with Ct
values ranging from 12 to 39.9 (median Ct value: 28.8) (Figure 3).
Fifty-five specimens with Ct values < 35 found to contain DNA
copies between 3.3 X 102 and 5.7 X
1010. Among them, 46 specimens were negative for RVA
and NoV and of which 71.7% were with severe and very severe disease
outcome. Analysis of the mean Ct values and viral load in specimens with
different subgroups showed no significant difference (Table 5). However,
the viral load in patients infected with HAdV-F strains was
significantly high (n=32; 5.24± 2.38) as compared to non HAdV-F strains
(n=29; 4.11± 1.61, p=0.036).
Among HAdV positive patients, 9, 28, 18 and 6 specimens showed Ct values
between 10-20, 20-30, 30-35 and 35-40 respectively (Table 6). The
distribution of patients with moderate, severe and very severe disease
outcome in different groups of Ct values was not significantly different
from each other (p=0.571, Table 6). Comparative analysis of the mean ±
SD values obtained for disease severity score among these groups was
without any significant difference. Analysis of moderate, severe and
very severe disease outcome in different groups of Ct values in HAdV-F
and non HAdV-F strains showed no significant difference (p= 0.299, Table
6)
Six specimens with Ct values >35 showed DNA copies between
2.7X102 and 0.69 per reaction and belong to genotype
HAdVF-40, HAdVF-41, HAdVA-31, HAdVA-12, HAdVC-5 and untypeable hexon
strain. Out of these six specimens, five belonged to patients with
severe disease outcome displaying dual infection with Norovirus in two
and RVA in one.