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, 9 (9), 2112-5

α2u-globulins Mediate Manipulation of Host Attractiveness in Toxoplasma gondii-Rattus Novergicus Association


α2u-globulins Mediate Manipulation of Host Attractiveness in Toxoplasma gondii-Rattus Novergicus Association

Anand Vasudevan et al. ISME J.


Uninfected female rats (Rattus novergicus) exhibit greater attraction to the males infected with protozoan parasite Toxoplasma gondii. This phenomenon is contrary to the aversion towards infected males observed in multitude of other host-parasite associations. In this report, we describe a proximate mechanism for this anomaly. We demonstrate that T. gondii infection enhances hepatic production and urinary excretion of α2u-globulins in rats. We further demonstrate that α2u-globulins are sufficient to recapitulate male sexual attractiveness akin to effects of the infection. This manipulation possibly results in greater horizontal transmission of this parasite between the infected male and the uninfected female. It supports the notion that in some evolutionary niches parasites can alter host sexual signaling, likely leading to an increased rate of sexual transmission.


Figure 1
Figure 1
The greater attractiveness of T. gondii-infected males was communicated by HMW, and not LMW, fraction of the male urine. Estrus females exhibited greater attraction to HMW fraction of the urine obtained from the infected males (a, black dots). N=16 females. ANOVA: P=0.514 for fractions; P=0.018 for infection status; P=0.007 for interaction. Abscissa and ordinate depict time spent in bisect containing urine from infected or control animals, respectively (in second, trial duration=1200 s). Solid circles depict data obtained from individual females. Gray diagonal line depicts chance (abscissa=ordinate). The attraction was not recapitulated by LMW fraction (<3 kDa) of the urine (a, gray dots). HMW obtained from infected animals was attractive to females even when combined with LMW of control urine (b). N=12 females. Mass spectroscopic analysis revealed major component of HMW fraction to be α2u-globulins.
Figure 2
Figure 2
Toxoplasma gondii infection increased α2u-globulins production in liver and excretion in urine. Infection enhanced α2u-globulins mRNA abundance in the liver (a). Ordinate depicts PCR cycles needed to reach a threshold when using α2u-globulins primers minus when using GAPDH primers (a housekeeping gene). Box plot depicts median, 25th percentile and 75th percentile. *P<0.05; exact Mann–Whitney test. N =7. Liver and urine from infected animals contained greater amounts of α2u-globulin protein. N=6 control, 8 infected (liver); N=7 (urine) (b). Ordinate depicts densitometric intensity, normalized to intensity of a pooled sample run in the same gel. Same pooled samples were used in all gels of the experiment. Creatinine-adjusted urine samples were used. Both groups exhibited comparable filtration rates of urine from the kidney (creatinine content; P>0.9) and a comparable tendency to place urine marks in a novel arena (P>0.9). *P<0.05 and **P<0.01; exact Mann–Whitney test. N=7. Renatured α2u-globulins postdialysis were sufficient to recapitulate greater attractiveness (c). Females exhibited attraction to FPLC-purified HMW fraction containing α2u-globulins, even after its denaturation in 3 m guanidinium chloride, subsequent dialysis and then renaturation in buffered physiological saline to remove all bound volatiles. N=12 females.

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