The mosquito-borne Zika virus (ZIKV) is one of the most feared viruses for pregnant women. Recent statistics justify this fear: Infants born to mothers infected with ZIKV during pregnancy face a risk of up to 42 percent of developing birth defects, including microcephaly (an abnormally small head and decreased brain volume). What do we know about how ZIKV causes damage to the developing brain? Researchers recently developed a mouse model for fetal brain defects associated with human ZIKV infection. To determine the effect of ZIKV on the number of neurons in the brain, ZIKV was injected into the brains of developing mouse embryos. Neurons were identified by staining sections of brain tissue with antibodies against NeuN, a neuron-specific protein, and the number of NeuN-positive cells per mm2 in specific regions was quantified. The results of three independent experiments are shown in the graph below. Use the P value provided to determine if the difference is significant or not (* means P< 0.05). Based on these results, what can you conclude?

Verified step by step guidance

1. Examine the graph provided to compare the number of NeuN-positive cells per mm2 in the brains of ZIKV-infected mouse embryos versus control embryos across the three independent experiments.
2. Identify the regions of the brain analyzed and note any significant differences in the number of neurons between the ZIKV-infected and control groups, indicated by a P value less than 0.05 (*).
3. Interpret the significance of the P values: if P < 0.05, it suggests that the differences in neuron numbers between the infected and control groups are statistically significant, implying a real effect of ZIKV on neuron numbers.
4. Analyze the overall trend across all experiments and regions to determine if ZIKV consistently leads to a decrease in neuron numbers in the developing brain.
5. Conclude based on the data whether ZIKV infection during embryonic development leads to a significant reduction in neuron numbers, contributing to the observed brain defects such as microcephaly.

Key Concepts

Zika Virus and Its Effects on Pregnancy

The Zika virus is a mosquito-borne pathogen that poses significant risks during pregnancy, particularly in causing severe birth defects such as microcephaly. Infection during pregnancy can disrupt normal fetal brain development, leading to a range of neurological issues. Understanding the mechanisms by which ZIKV affects the developing brain is crucial for assessing its impact on infant health.

Mouse Model in Biomedical Research

Mouse models are widely used in biomedical research to study human diseases due to their genetic, biological, and behavioral similarities to humans. In the context of ZIKV research, injecting the virus into developing mouse embryos allows scientists to observe the direct effects on brain development and neuron formation. This approach helps in understanding the pathophysiology of ZIKV-induced birth defects.

Statistical Significance and P-Values

Statistical significance is a measure that helps determine whether the results of an experiment are likely due to chance. The P-value indicates the probability of observing the results if the null hypothesis is true; a P-value less than 0.05 is commonly considered statistically significant. In the context of the ZIKV study, analyzing the P-value helps researchers conclude whether the differences in neuron counts are meaningful and not due to random variation.