Table 2.

Di-nucleotide bias for six RNA viruses.

	BCoV			MHV			SARS			ABV			HCoV			PDV			Average z value across 31 viruses
Di-nucleotide	N(w)	E(w)	z	N(w)	E(w)	z	N(w)	E(w)	z	N(w)	E(w)	z	N(w)	E(w)	z	N(w)	E(w)	z
CG	497	1034	-103.81	798	1342	-104.39	566	1235	-121-14	486	976	-109.69	487	979	-95.94	684	1226	-102.03	-77.31
GC	1344	1037	62.19	1694	1341	62.33	1432	1236	36.12	1147	970	35.96	1164	976	37.86	1416	1228	35.05	5.74
AU	2845	3007	-26.44	2499	2614	-19.25	2234	2594	-58.91	2200	2642	-76.99	2092	2556	-81.97	1976	2296	-55.43	-15.54
UA	2818	3000	-30.10	2404	2616	-35.12	2080	2594	-87.64	2409	2641	-42.42	2033	2554	-84.51	1965	2299	-53.83	-52.48
AG	1824	1848	-4.25	1968	1941	4.77	1749	1760	-2.00	1844	1728	21.13	1416	1601	-34.78	1537	1579	-7.12	3.80
GA	1629	1849	-39.08	1745	1941	-32.74	1677	1764	-16.43	1505	1730	-39.47	1397	1598	-36.09	1358	1581	-38.05	-1.33
AC	1371	1303	12.93	1384	1458	-13.50	1978	1695	50.18	1474	1292	35.28	1558	1236	58.96	1594	1332	50.25	5.42
CA	1594	1297	56.03	1705	1453	46.19	2203	1695	87.29	1603	1290	59.90	1638	1234	74.68	1783	1327	83.96	49.99
CU	1801	1674	22.52	1874	1806	12.28	2190	1814	67.50	1661	1487	31.50	1724	1568	28.13	1953	1784	29.95	16.50
UC	1179	1674	-88.35	1296	1802	-94.30	1552	1815	-46.36	1127	1482	-65.41	1130	1568	-79.37	1410	1781	-67.80	-17.49
GU	2449	2394	9.10	2473	2402	11.92	1868	1898	-5.35	2154	1982	29.46	2240	2044	34.60	2262	2119	23.86	-7.13
UG	3101	2392	120.25	3146	2408	128.13	2663	1897	137.30	2476	1983	87.74	2898	2040	152.24	2814	2117	126.99	65.79

The di-nucleotide bias in six RNA viruses. The z value quantifies the di-nucleotide bias as defined in equation 1. N (w) and E (w) are actual and expected frequency of occurrence for word w. The last column is the average z value across 31 RNA viruses.